TY - GEN A1 - Doriti, Afroditi A1 - Brosnan, Sarah M. A1 - Weidner, Steffen M. A1 - Schlaad, Helmut T1 - Synthesis of polysarcosine from air and moisture stable N-phenoxycarbonyl-N-methylglycine assisted by tertiary amine base N2 - Polysarcosine (Mn = 3650–20 000 g mol−1, Đ ∼ 1.1) was synthesized from the air and moisture stable N-phenoxycarbonyl-N-methylglycine. Polymerization was achieved by in situ transformation of the urethane precursor into the corresponding N-methylglycine-N-carboxyanhydride, when in the presence of a non-nucleophilic tertiary amine base and a primary amine initiator. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 255 KW - acids KW - activated urethane derivatives KW - carboxyanhydrides KW - copolymers KW - phosgene-free synthesis KW - polypeptides KW - ring-opening polymerization Y1 - 2016 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-95852 SP - 3067 EP - 3070 ER - TY - GEN A1 - Hardy, John G. A1 - Torres-Rendon, Jose Guillermo A1 - Leal-Egaña, Aldo A1 - Walther, Andreas A1 - Schlaad, Helmut A1 - Cölfen, Helmut A1 - Scheibel, Thomas R. T1 - Biomineralization of engineered spider silk protein-based composite materials for bone tissue engineering N2 - Materials based on biodegradable polyesters, such as poly(butylene terephthalate) (PBT) or poly(butylene terephthalate-co-poly(alkylene glycol) terephthalate) (PBTAT), have potential application as pro-regenerative scaffolds for bone tissue engineering. Herein, the preparation of films composed of PBT or PBTAT and an engineered spider silk protein, (eADF4(C16)), that displays multiple carboxylic acid moieties capable of binding calcium ions and facilitating their biomineralization with calcium carbonate or calcium phosphate is reported. Human mesenchymal stem cells cultured on films mineralized with calcium phosphate show enhanced levels of alkaline phosphatase activity suggesting that such composites have potential use for bone tissue engineering. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 359 KW - spider silk KW - recombinant protein KW - biodegradable polymers KW - biomaterials KW - biomineralization KW - bone tissue engineering Y1 - 2017 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-400519 ER - TY - GEN A1 - Behrendt, Felix Nicolas A1 - Schlaad, Helmut T1 - Metathesis polymerization of cystine-based macrocycles N2 - Macrocycles based on L-cystine were synthesized by ring-closing metathesis (RCM) and subsequently polymerized by entropy-driven ring-opening metathesis polymerization (ED-ROMP). Monomer conversion reached ∼80% in equilibrium and the produced poly(ester-amine-disulfide-alkene)s exhibited apparent molar masses (Mappw) of up to 80 kDa and dispersities (Đ) of ∼2. The polymers can be further functionalized with acid anhydrides and degraded by reductive cleavage of the main-chain disulfide. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 329 Y1 - 2016 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-395080 ER - TY - GEN A1 - Hoogenboom, Richard A1 - Schlaad, Helmut T1 - Thermoresponsive poly(2-oxazoline)s, polypeptoids, and polypeptides N2 - This review covers the recent advances in the emerging field of thermoresponsive polyamides or polymeric amides, i.e., poly(2-oxazoline)s, polypeptoids, and polypeptides, with a specific focus on structure–thermoresponsive property relationships, self-assembly, and applications. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 328 Y1 - 2016 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-395022 ER - TY - GEN A1 - Vacogne, Charlotte D. A1 - Brosnan, Sarah M. A1 - Masic, Admir A1 - Schlaad, Helmut T1 - Fibrillar gels via the self-assembly of poly(L-glutamate)-based statistical copolymers N2 - Polypeptides having secondary structures often undergo self-assembly which can extend over multiple length scales. Poly(γ-benzyl-L-glutamate) (PBLG), for example, folds into α-helices and forms physical organogels, whereas poly(L-glutamic acid) (PLGA at acidic pH) or poly(L-glutamate) (PLG at neutral/basic pH) do not form hydrogels. We explored the gelation of modified PBLG and investigated the deprotection of the carboxylic acid moieties in such gels to yield unique hydrogels. This was accomplished through photo-crosslinking gelation of poly(γ-benzyl-L-glutamate-co-allylglycine) statistical copolymers in toluene, tetrahydrofuran, and 1,4-dioxane. Unlike most polymer-based chemical gels, our gels were prepared from dilute solutions (<20 g L−1, i.e., <2% w/v) of low molar mass polymers. Despite such low concentrations and molar masses, our dioxane gels showed high mechanical stability and little shrinkage; remarkably, they also exhibited a porous fibrillar network. Deprotection of the carboxylic acid moieties in dioxane gels yielded pH responsive and highly absorbent PLGA/PLG-based hydrogels (swelling ratio of up to 87), while preserving the network structure, which is an unprecedented feature in the context of crosslinked PLGA gels. These outstanding properties are highly attractive for biomedical materials. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 301 Y1 - 2015 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-102289 SP - 5040 EP - 5052 ER - TY - GEN A1 - Vacogne, Charlotte D. A1 - Schlaad, Helmut T1 - Primary ammonium/tertiary amine-mediated controlled ring opening polymerisation of amino acid N-carboxyanhydrides N2 - Stable commercial primary ammonium chlorides were combined with tertiary amines to initiate the controlled ring opening polymerisation of amino acid N-carboxyanhydrides to yield polypeptides with defined end group structure, predetermined molar mass and narrow molar mass distribution. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 307 Y1 - 2015 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-102718 SP - 15645 EP - 15648 ER - TY - GEN A1 - Raju, Rajarshi Roy A1 - Liebig, Ferenc A1 - Hess, Andreas A1 - Schlaad, Helmut A1 - Koetz, Joachim T1 - Temperature-triggered reversible breakdown of polymer-stabilized olive BT - silicone oil Janus emulsions T2 - Postprints der Universität Potsdam Mathematisch-Naturwissenschaftliche Reihe N2 - A one-step moderate energy vibrational emulsification method was successfully employed to produce thermo-responsive olive/silicone-based Janus emulsions stabilized by poly(N,N-diethylacrylamide) carrying 0.7 mol% oleoyl side chains. Completely engulfed emulsion droplets remained stable at room temperature and could be destabilized on demand upon heating to the transition temperature of the polymeric stabilizer. Time-dependent light micrographs demonstrate the temperature-induced breakdown of the Janus droplets, which opens new aspects of application, for instance in biocatalysis. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 751 KW - microgels KW - step Y1 - 2019 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-436461 SN - 1866-8372 IS - 751 SP - 19271 EP - 19277 ER - TY - JOUR A1 - Kedracki, Dawid A1 - Chekini, Mahshid A1 - Maroni, Plinio A1 - Schlaad, Helmut A1 - Nardin, Corinne T1 - Synthesis and Self-Assembly of a DNA Molecular Brush JF - Biomacromolecules : an interdisciplinary journal focused at the interface of polymer science and the biological sciences N2 - We report herein on the polymer-crystallization-assisted thiol-ene photosynthesis of an amphiphilic comb/graft DNA copolymer, or molecular brush, composed of a hydrophobic poly(2-oxazoline) backbone and hydrophilic short single-stranded nucleic acid grafts. Coupling efficiencies are above 60% and thus higher as compared with the straight solid-phase-supported synthesis of amphiphilic DNA block copolymers. The DNA molecular brushes self-assemble into sub-micron-sized spherical structures in water as evidenced by light scattering as well as atomic force and electron microscopy imaging. The nucleotide sequences remain functional, as assessed by UV and fluorescence spectroscopy subsequent to isoindol synthesis at the surface of the structures. The determination of a vesicular morphology is supported by encapsulation and subsequent spectroscopy monitoring of the release of a water-soluble dye and spectroscopic quantification of the hybridization efficiency (30% in average) of the functional nucleic acid strands engaged in structure formation: about one-half of the nucleotide sequences are available for hybridization, whereas the other half are hindered within the self-assembled structure. Because speciation between complementary and non complementary sequences in the medium could be ascertained by confocal laser scanning microscopy, the stable self-assembled molecular brushes demonstrate the potential for sensing applications. Y1 - 2014 U6 - https://doi.org/10.1021/bm5008713 SN - 1525-7797 SN - 1526-4602 VL - 15 IS - 9 SP - 3375 EP - 3382 PB - American Chemical Society CY - Washington ER - TY - INPR A1 - Schlaad, Helmut T1 - Thiol-X chemistry in polymer science T2 - Polymer : the international journal for the science and technology of polymers Y1 - 2014 U6 - https://doi.org/10.1016/j.polymer.2014.09.020 SN - 0032-3861 SN - 1873-2291 VL - 55 IS - 22 SP - 5509 EP - 5510 PB - Elsevier CY - Oxford ER - TY - JOUR A1 - Guiet, Amandine A1 - Goebel, Caren A1 - Klingan, Katharina A1 - Lublow, Michael A1 - Reier, Tobias A1 - Vainio, Ulla A1 - Kraehnert, Ralph A1 - Schlaad, Helmut A1 - Strasser, Peter A1 - Zaharieva, Ivelina A1 - Dau, Holger A1 - Driess, Matthias A1 - Polte, Joerg A1 - Fischer, Anna T1 - Hydrophobic Nanoreactor Soft-Templating: A Supramolecular Approach to Yolk@Shell Materials JF - Advanced functional materials N2 - Due to their unique morphology-related properties, yolk@shell materials are promising materials for catalysis, drug delivery, energy conversion, and storage. Despite their proven potential, large-scale applications are however limited due to demanding synthesis protocols. Overcoming these limitations, a simple soft-templated approach for the one-pot synthesis of yolk@shell nanocomposites and in particular of multicore metal nanoparticle@metal oxide nanostructures (M-NP@MOx) is introduced. The approach here, as demonstrated for Au-NP@ITOTR (ITOTR standing for tin-rich ITO), relies on polystyrene-block-poly(4-vinylpyridine) (PS-b-P4VP) inverse micelles as two compartment nanoreactor templates. While the hydrophilic P4VP core incorporates the hydrophilic metal precursor, the hydrophobic PS corona takes up the hydrophobic metal oxide precursor. As a result, interfacial reactions between the precursors can take place, leading to the formation of yolk@shell structures in solution. Once calcined these micelles yield Au-NP@ITOTR nanostructures, composed of multiple 6 nm sized Au NPs strongly anchored onto the inner surface of porous 35 nm sized ITOTR hollow spheres. Although of multicore nature, only limited sintering of the metal nanoparticles is observed at high temperatures (700 degrees C). In addition, the as-synthesized yolk@shell structures exhibit high and stable activity toward CO electrooxidation, thus demonstrating the applicability of our approach for the design of functional yolk@shell nanocatalysts. KW - inverse micelles KW - nanoreactor KW - polystyrene-block-poly(4-vinylpyridine) KW - soft-templating KW - tin-rich ITO KW - yolk@shell materials Y1 - 2015 U6 - https://doi.org/10.1002/adfm.201502388 SN - 1616-301X SN - 1616-3028 VL - 25 IS - 39 SP - 6228 EP - 6240 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Secker, Christian A1 - Brosnan, Sarah M. A1 - Limberg, Felix Rolf Paul A1 - Braun, Ulrike A1 - Trunk, Matthias A1 - Strauch, Peter A1 - Schlaad, Helmut T1 - Thermally Induced Crosslinking of Poly(N-Propargyl Glycine) JF - Macromolecular chemistry and physics N2 - As polypeptoids become increasingly popular, they present a more soluble and processable alternative to natural and synthetic polypeptides; the breadth of their potential functionality slowly comes into focus. This report analyzes the ability of an alkyne-functionalized polypeptoid, poly(N-propargyl glycine), to crosslink upon heating. The crosslinking process is analyzed by thermal analysis (differential scanning calorimetry and thermogravimetric analysis), Fourier-transform infrared, electron paramagnetic resonance, and solid-state NMR spectroscopy. While a precise mechanism cannot be confidently assigned, it is clear that the reaction proceeds by a radical mechanism that exclusively involves the alkyne functionality, which, upon crosslinking, yields alkene and aromatic products. KW - Fourier-transform infrared KW - metal-free crosslinking KW - polypeptoid KW - propargyl KW - solid-state NMR Y1 - 2015 U6 - https://doi.org/10.1002/macp.201500223 SN - 1022-1352 SN - 1521-3935 VL - 216 IS - 21 SP - 2080 EP - 2085 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Madaan, Nitesh A1 - Romriell, Naomi A1 - Tuscano, Joshua A1 - Schlaad, Helmut A1 - Linford, Matthew R. T1 - Introduction of thiol moieties, including their thiol-ene reactions and air oxidation, onto polyelectrolyte multilayer substrates JF - Journal of colloid and interface science KW - Thiol-ene KW - Layer-by-layer KW - XPS KW - ToF-SIMS KW - Hydrophobic KW - AFM KW - Ellipsometry Y1 - 2015 U6 - https://doi.org/10.1016/j.jcis.2015.08.017 SN - 0021-9797 SN - 1095-7103 VL - 459 SP - 199 EP - 205 PB - Elsevier CY - San Diego ER - TY - JOUR A1 - Koshkina, Olga A1 - Lang, Thomas A1 - Thiermann, Raphael A1 - Docter, Dominic A1 - Stauber, Roland H. A1 - Secker, Christian A1 - Schlaad, Helmut A1 - Weidner, Steffen A1 - Mohr, Benjamin A1 - Maskos, Michael A1 - Bertin, Annabelle T1 - Temperature-Triggered Protein Adsorption on Polymer-Coated Nanoparticles in Serum JF - Langmuir N2 - The protein corona, which forms on the nanoparticle's surface in most biological media, determines the nanoparticle's physicochemical characteristics. The formation of the protein corona has a significant impact on the biodistribution and clearance of nanoparticles in vivo. Therefore, the ability to influence the formation of the protein corona is essential to most biomedical applications, including drug delivery and imaging. In this study, we investigate the protein adsorption on nanoparticles with a hydrodynamic radius of 30 nm and a coating of thermoresponsive poly(2-isopropyl-2-oxazoline) in serum. Using multiangle dynamic light scattering (DLS) we demonstrate that heating of the nanoparticles above their phase separation temperature induces the formation of agglomerates, with a hydrodynamic radius of 1 mu m. In serum, noticeably stronger agglomeration occurs at lower temperatures compared to serum-free conditions. Cryogenic transmission electron microscopy (cryo-TEM) revealed a high packing density of agglomerates when serum was not present. In contrast, in the presence of serum, agglomerated nanoparticles were loosely packed, indicating that proteins are intercalated between them. Moreover, an increase in protein content is observed upon heating, confirming that protein adsorption is induced by the alteration of the surface during phase separation. After cooling and switching the surface back, most of the agglomerates were dissolved and the main fraction returned to the original size of approximately 30 nm as shown by asymmetrical flow-field flow fractionation (AF-FFF) and DLS. Furthermore, the amounts of adsorbed proteins are similar before and after heating the nanoparticles to above their phase-separation temperature. Overall, our results demonstrate that the thermoresponsivity of the polymer coating enables turning the corona formation on nanoparticles on and off in situ. As the local heating of body areas can be easily done in vivo, the thermoresponsive coating could potentially be used to induce the agglomeration of nanopartides and proteins and the accumulation of nanoparticles in a targeted body region. Y1 - 2015 U6 - https://doi.org/10.1021/acs.langmuir.5b00537 SN - 0743-7463 VL - 31 IS - 32 SP - 8873 EP - 8881 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - Secker, Christian A1 - Brosnan, Sarah M. A1 - Luxenhofer, Robert A1 - Schlaad, Helmut T1 - Poly(alpha-Peptoid)s Revisited: Synthesis, Properties, and Use as Biomaterial JF - Macromolecular bioscience N2 - Polypeptoids have been of great interest in the polymer science community since the early half of the last century; however, they had been basically forgotten materials until the last decades in which they have enjoyed an exciting revival. In this mini-review, we focus on the recent developments in polypeptoid chemistry, with particular focus on polymers synthesized by the ring-opening polymerization (ROP) of amino acid N-carboxyanhydrides (NCAs). Specifically, we will review traditional monomer synthesis (such as Leuchs, Katchalski, and Kricheldorf) and recent advances in polymerization methods to yield both linear, cyclic, and functional polymers, solution and bulk thermal properties, and preliminary results on the use of polypeptoids as biomaterials (i.e immunogenicity, biodistribution, degradability, and drug delivery). KW - amino acid N-carboxyanhydride (NCA) KW - biomaterials KW - peptides KW - properties KW - ring-opening polymerization Y1 - 2015 U6 - https://doi.org/10.1002/mabi.201500023 SN - 1616-5187 SN - 1616-5195 VL - 15 IS - 7 SP - 881 EP - 891 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Brosnan, Sarah M. A1 - Schlaad, Helmut A1 - Antonietti, Markus T1 - Aqueous Self-Assembly of Purely Hydrophilic Block Copolymers into Giant Vesicles JF - Angewandte Chemie : a journal of the Gesellschaft Deutscher Chemiker ; International edition N2 - Self-assembly of macromolecules is fundamental to life itself, and historically, these systems have been primitively mimicked by the development of amphiphilic systems, driven by the hydrophobic effect. Herein, we demonstrate that self-assembly of purely hydrophilic systems can be readily achieved with similar ease and success. We have synthesized double hydrophilic block copolymers from polysaccharides and poly(ethylene oxide) or poly(sarcosine) to yield high molar mass diblock copolymers through oxime chemistry. These hydrophilic materials can easily assemble into nanosized (<500nm) and microsized (>5m) polymeric vesicles depending on concentration and diblock composition. Because of the solely hydrophilic nature of these materials, we expect them to be extraordinarily water permeable systems that would be well suited for use as cellular mimics. KW - block copolymers KW - polymersomes KW - polysaccharides KW - self-assembly KW - vesicles Y1 - 2015 U6 - https://doi.org/10.1002/anie.201502100 SN - 1433-7851 SN - 1521-3773 VL - 54 IS - 33 SP - 9715 EP - 9718 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Zou, Hua A1 - Schlaad, Helmut T1 - Thermoresponsive PNIPAM/Silica Nanoparticles by Direct Photopolymerization in Aqueous Media JF - Journal of polymer science : A, Polymer chemistry N2 - This article presents a simple and facile method to fabricate thermoresponsive polymer-grafted silica particles by direct surface-initiated photopolymerization of N-isopropylacrylamide (NIPAM). This method is based on silica particles bearing thiol functionalities, which are transformed into thiyl radicals by irradiation with UV light to initiate the polymerization of NIPAM in aqueous media at room temperature. The photopolymerization of NIPAM could be applied to smaller thiol-functionalized particles (approximate to 48 nm) as well as to larger particles (approximate to 692 nm). Hollow poly(NIPAM) capsules could be formed after etching away the silica cores from the composite particles. It is possible to produce tailor-made composite particles or capsules for particular applications by extending this approach to other vinyl monomers. (c) 2015 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 2015, 53, 1260-1267 KW - nanocomposites KW - nanoparticles KW - photopolymerization KW - silica nanoparticles KW - surface-initiated photopolymerization KW - thermoresponsive KW - thiol Y1 - 2015 U6 - https://doi.org/10.1002/pola.27593 SN - 0887-624X SN - 1099-0518 VL - 53 IS - 10 SP - 1260 EP - 1267 PB - Wiley-Blackwell CY - Hoboken ER - TY - JOUR A1 - Kedracki, Dawid A1 - Filippov, Sergey K. A1 - Gour, Nidhi A1 - Schlaad, Helmut A1 - Nardin, Corinne T1 - Formation of DNA-Copolymer Fibrils Through an Amyloid-Like Nucleation Polymerization Mechanism JF - Macromolecular rapid communications N2 - Conjugation of a hydrophobic poly(2-oxazoline) bearing tertiary amide groups along its backbone with a short single stranded nucleotide sequence results in an amphiphilic comb/graft copolymer, which organizes in fibrils upon direct dissolution in water. Supported by circular dichroism, atomic force microscopy, transmission electron microscopy, and scattering data, fibrils are formed through inter- and intramolecular hydrogen bonding between hydrogen accepting amide groups along the polymer backbone and hydrogen donating nucleic acid grafts leading to the formation of hollow tubes. KW - DNA copolymers KW - fibers KW - hydrogen bonding KW - nucleation polymerization KW - self-assembly Y1 - 2015 U6 - https://doi.org/10.1002/marc.201400728 SN - 1022-1336 SN - 1521-3927 VL - 36 IS - 8 SP - 768 EP - 773 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Vacogne, Charlotte D. A1 - Brosnan, Sarah M. A1 - Masic, Admir A1 - Schlaad, Helmut T1 - Fibrillar gels via the self-assembly of poly(L-glutamate)-based statistical copolymers JF - Polymer Chemistry N2 - Polypeptides having secondary structures often undergo self-assembly which can extend over multiple length scales. Poly(gamma-benzyl-L-glutamate) (PBLG), for example, folds into a-helices and forms physical organogels, whereas poly(L-glutamic acid) (PLGA at acidic pH) or poly(L-glutamate) (PLG at neutral/basic pH) do not form hydrogels. We explored the gelation of modified PBLG and investigated the deprotection of the carboxylic acid moieties in such gels to yield unique hydrogels. This was accomplished through photo-crosslinking gelation of poly(gamma-benzyl-L-glutamate-co-allylglycine) statistical copolymers in toluene, tetrahydrofuran, and 1,4-dioxane. Unlike most polymer-based chemical gels, our gels were prepared from dilute solutions (<20 g L-1, i.e., <2% w/v) of low molar mass polymers. Despite such low concentrations and molar masses, our dioxane gels showed high mechanical stability and little shrinkage; remarkably, they also exhibited a porous fibrillar network. Deprotection of the carboxylic acid moieties in dioxane gels yielded pH responsive and highly absorbent PLGA/PLG-based hydrogels (swelling ratio of up to 87), while preserving the network structure, which is an unprecedented feature in the context of crosslinked PLGA gels. These outstanding properties are highly attractive for biomedical materials. Y1 - 2015 U6 - https://doi.org/10.1039/c5py00491h SN - 1759-9954 SN - 1759-9962 VL - 6 IS - 28 SP - 5040 EP - 5052 PB - Royal Society of Chemistry CY - Cambridge ER - TY - JOUR A1 - Tritschler, U. A1 - Beck, F. A1 - Schlaad, Helmut A1 - Cölfen, Helmut T1 - Electrochromic properties of self-organized multifunctional V2O5-polymer hybrid films JF - Journal of materials chemistry : C, Materials for optical and electronic devices N2 - Bio-inspired V2O5-polymer hybrid films were prepared following a one-step self-organization procedure based on liquid crystal formation of organic and inorganic components. These materials were previously reported to exhibit advantageous mechanical properties, comparable to biomaterials, such as human bone and dentin. Here, we show that these hybrid films prepared via a fast and simple synthesis procedure have an additional function as an electrochromic material, exhibiting a long-term cycle stability under alternating potentials. The structures were found to remain intact without visible changes after more than hundred switching cycles and storing the devices for several weeks. Consequently, this multifunctional V2O5-polymer hybrid system shows great promise for various technical applications. Y1 - 2015 U6 - https://doi.org/10.1039/c4tc02138j SN - 2050-7526 SN - 2050-7534 VL - 3 IS - 5 SP - 950 EP - 954 PB - Royal Society of Chemistry CY - Cambridge ER - TY - JOUR A1 - Secker, Christian A1 - Robinson, Joshua W. A1 - Schlaad, Helmut T1 - Alkyne-X modification of polypeptoids JF - European polymer journal N2 - Poly(N-propargyl glycine) (PNPG) can be readily prepared by ring-opening polymerization of N-propargyl glycine N-carboxyanhydride (NCA) and modified using various addition reactions such as copper catalyzed [3+2] cycloaddition of azide, radical (photo-)addition of thiol, nucleophilic addition of ethylene oxide, and thermal induced cross-linking. It is demonstrated that PNPG can serve as a modular platform to produce a bibliography of novel functional polypeptoid or pseudopeptide materials, including polypeptoid ionic liquids and graft copolymers. KW - Polypeptoid KW - NCA KW - Post-polymerization modification KW - Click chemistry Y1 - 2015 U6 - https://doi.org/10.1016/j.eurpolymj.2014.08.028 SN - 0014-3057 SN - 1873-1945 VL - 62 SP - 394 EP - 399 PB - Elsevier CY - Oxford ER - TY - JOUR A1 - Vacogne, Charlotte D. A1 - Schlaad, Helmut T1 - Primary ammonium/tertiary amine-mediated controlled ring opening polymerisation of amino acid N-carboxyanhydrides JF - Chemical communications N2 - Stable commercial primary ammonium chlorides were combined with tertiary amines to initiate the controlled ring opening polymerisation of amino acid N-carboxyanhydrides to yield polypeptides with defined end group structure, predetermined molar mass and narrow molar mass distribution. Y1 - 2015 U6 - https://doi.org/10.1039/c5cc06905j SN - 1359-7345 SN - 1364-548X VL - 51 IS - 86 SP - 15645 EP - 15648 PB - Royal Society of Chemistry CY - Cambridge ER - TY - JOUR A1 - Koshkina, Olga A1 - Westmeier, Dana A1 - Lang, Thomas A1 - Bantz, Christoph A1 - Hahlbrock, Angelina A1 - Würth, Christian A1 - Resch-Genger, Ute A1 - Braun, Ulrike A1 - Thiermann, Raphael A1 - Weise, Christoph A1 - Eravci, Murat A1 - Mohr, Benjamin A1 - Schlaad, Helmut A1 - Stauber, Roland H. A1 - Docter, Dominic A1 - Bertin, Annabelle A1 - Maskos, Michael T1 - Tuning the Surface of Nanoparticles: Impact of Poly(2-ethyl-2-oxazoline) on Protein Adsorption in Serum and Cellular Uptake JF - Macromolecular bioscience N2 - Due to the adsorption of biomolecules, the control of the biodistribution of nanoparticles is still one of the major challenges of nanomedicine. Poly(2-ethyl-2-oxazoline) (PEtOx) for surface modification of nanoparticles is applied and both protein adsorption and cellular uptake of PEtOxylated nanoparticles versus nanoparticles coated with poly(ethylene glycol) (PEG) and non-coated positively and negatively charged nanoparticles are compared. Therefore, fluorescent poly(organosiloxane) nanoparticles of 15 nm radius are synthesized, which are used as a scaffold for surface modification in a grafting onto approach. With multi-angle dynamic light scattering, asymmetrical flow field-flow fractionation, gel electrophoresis, and liquid chromatography-mass spectrometry, it is demonstrated that protein adsorption on PEtOxylated nanoparticles is extremely low, similar as on PEGylated nanoparticles. Moreover, quantitative microscopy reveals that PEtOxylation significantly reduces the non-specific cellular uptake, particularly by macrophage-like cells. Collectively, studies demonstrate that PEtOx is a very effective alternative to PEG for stealth modification of the surface of nanoparticles. KW - cellular uptake KW - nanoparticles KW - poly(2-ethyl-2oxazoline) KW - poly(ethylene glycol) KW - protein adsorption Y1 - 2016 U6 - https://doi.org/10.1002/mabi.201600074 SN - 1616-5187 SN - 1616-5195 VL - 16 SP - 1287 EP - 1300 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Sun, Jing A1 - Cernoch, Peter A1 - Völkel, Antje A1 - Wei, Yuhan A1 - Ruokolainen, Janne A1 - Schlaad, Helmut T1 - Aqueous Self-Assembly of a Protein-Mimetic Ampholytic Block Copolypeptide JF - Macromolecules : a publication of the American Chemical Society N2 - This report describes the aggregation behavior of an ABC-type ampholytic block copolypeptide, poly(ethylene oxide)-block-poly(L-lysine)-block-poly(L-glutamate), in aqueous media in dependence of pH. Polypeptide secondary structures and self-assemblies are investigated by circular dichroism (CD), Fourier transform infrared (FT-IR) and NMR spectroscopy, zeta potential measurements, analytical ultracentrifugation (AUC), dynamic/static light scattering (DLS/SLS), and cryogenic transmission electron microscopy (cryoTEM). The polymer chains tend to form vesicles when the hydrophobic polypeptide helix is located at the chain end (acidic pH) and are existing as single chains when it is located in the center and flanked by the two hydrophilic segments (basic pH). Precipitation occurs in the intermediate pH range due to polyion complexation of the charged polypeptide segments. Y1 - 2016 U6 - https://doi.org/10.1021/acs.macromol.6b00817 SN - 0024-9297 SN - 1520-5835 VL - 49 SP - 5494 EP - 5501 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - Hardy, John G. A1 - Torres-Rendon, Jose Guillermo A1 - Leal-Egana, Aldo A1 - Walther, Andreas A1 - Schlaad, Helmut A1 - Coelfen, Helmut A1 - Scheibel, Thomas R. T1 - Biomineralization of Engineered Spider Silk Protein-Based Composite Materials for Bone Tissue Engineering JF - Materials N2 - Materials based on biodegradable polyesters, such as poly(butylene terephthalate) (PBT) or poly(butylene terephthalate-co-poly(alkylene glycol) terephthalate) (PBTAT), have potential application as pro-regenerative scaffolds for bone tissue engineering. Herein, the preparation of films composed of PBT or PBTAT and an engineered spider silk protein, (eADF4(C16)), that displays multiple carboxylic acid moieties capable of binding calcium ions and facilitating their biomineralization with calcium carbonate or calcium phosphate is reported. Human mesenchymal stem cells cultured on films mineralized with calcium phosphate show enhanced levels of alkaline phosphatase activity suggesting that such composites have potential use for bone tissue engineering. KW - spider silk KW - recombinant protein KW - biodegradable polymers KW - biomaterials KW - biomineralization KW - bone tissue engineering Y1 - 2016 U6 - https://doi.org/10.3390/ma9070560 SN - 1996-1944 VL - 9 SP - 93 EP - 108 PB - MDPI CY - Basel ER - TY - JOUR A1 - Vacogne, Charlotte D. A1 - Schopferer, Michael A1 - Schlaad, Helmut T1 - Physical Gelation of alpha-Helical Copolypeptides JF - Biomacromolecules : an interdisciplinary journal focused at the interface of polymer science and the biological sciences N2 - Owing to its rod-like alpha-helical secondary structure, the synthetic polypeptide poly(gamma-benzyl-L-glutamate) (PBLG) can form physical and thermoreversible gels in helicogenic solvents such as toluene. The versatility of PBLG can be increased by introducing functionalizable comonomers, such as allylglycine (AG). In this work we examined the secondary structure of PBLG and a series of statistical poly(gamma-benzyl-L-glutamate-co-allylglycine) copolypeptides, varying in composition and chain length, by circular dichroism (CD), Fourier-transform infrared (FTIR) and Raman spectroscopy, and wide-angle X-ray scattering (WAXS). The secondary structure of PBLG and the copolypeptides presented dissimilarities that increased with increasing AG molar fraction, especially when racemic AG units were incorporated. The physical gelation behavior of these copolypeptides was analyzed by temperature-sweep H-1 NMR and rheological measurements. The study revealed that both copolypeptide composition and chain length affected secondary structure, gelation temperature, and gel stiffness. Y1 - 2016 U6 - https://doi.org/10.1021/acs.biomac.6b00427 SN - 1525-7797 SN - 1526-4602 VL - 17 SP - 2384 EP - 2391 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - Guiet, Amandine A1 - Unmüssig, Tobias A1 - Göbel, Caren A1 - Vainio, Ulla A1 - Wollgarten, Markus A1 - Driess, Matthias A1 - Schlaad, Helmut A1 - Polte, Jörg A1 - Fischer, Anna T1 - Yolk@Shell Nanoarchitectures with Bimetallic Nanocores - Synthesis and Electrocatalytic Applications JF - Earth & planetary science letters KW - AgAu alloy nanoparticles KW - tin-rich ITO KW - yolk@shell materials KW - nanoreactor KW - soft-templating KW - inverse micelles KW - polystyrene-block-poly(4-vinylpyridine) Y1 - 2016 U6 - https://doi.org/10.1021/acsami.6b06595 SN - 1944-8244 VL - 8 SP - 28019 EP - 28029 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - Demirel, A. Levent A1 - Guner, Pinar Tatar A1 - Verbraeken, Bart A1 - Schlaad, Helmut A1 - Schubert, Ulrich S. A1 - Hoogenboom, Richard T1 - Revisiting the Crystallization of Poly(2-alkyl-2-oxazoline)s JF - Journal of polymer science : B, Polymer physics N2 - Poly(2-alkyl-2-oxazoline)s (PAOx) exhibit different crystallization behavior depending on the length of the alkyl side chain. PAOx having methyl, ethyl, or propyl side chains do not show any bulk crystallization. Crystallization in the heating cycle, that is, cold crystallization, is observed for PAOx with butyl and pentyl side chains. For PAOx with longer alkyl side chains crystallization occurs in the cooling cycle. The different crystallization behavior is attributed to the different polymer chain mobility in line with the glass transition temperature (T-g) dependency on alkyl side chain length. The decrease in chain mobility with decreasing alkyl side chain length hinders the relaxation of the polymer backbone to the thermodynamic equilibrium crystalline structure. Double melting behavior is observed for PButOx and PiPropOx which is explained by the melt-recrystallization mechanism. Isothermal crystallization experiments of PButOx between 60 and 90 degrees C and PiPropOx between 90 and 150 degrees C show that PAOx can crystallize in bulk when enough time is given. The decrease of Tg and the corresponding increase in chain mobility at T > T-g with increasing alkyl side chain length can be attributed to an increasing distance between the polymer backbones and thus decreasing average strength of amide dipole interactions. (C) 2015 Wiley Periodicals, Inc. KW - chain mobility KW - crystallization KW - differential scanning calorimetry (DSC) KW - effect of alkyl side chains KW - glass transition temperature KW - melt KW - melt-recrystallization KW - polymer crystallization Y1 - 2016 U6 - https://doi.org/10.1002/polb.23967 SN - 0887-6266 SN - 1099-0488 VL - 54 SP - 721 EP - 729 PB - Wiley-Blackwell CY - Hoboken ER - TY - JOUR A1 - Tritschler, Ulrich A1 - Zlotnikov, Igor A1 - Fratzl, Peter A1 - Schlaad, Helmut A1 - Gruener, Simon A1 - Coelfen, Helmut T1 - Gas barrier properties of bio-inspired Laponite-LC polymer hybrid films JF - PLoS one N2 - Bio-inspired Laponite (clay)-liquid crystal (LC) polymer composite materials with high clay fractions (>80%) and a high level of orientation of the clay platelets, i.e. with structural features similar to the ones found in natural nacre, have been shown to exhibit a promising behavior in the context of reduced oxygen transmission. Key characteristics of these bio-inspired composite materials are their high inorganic content, high level of exfoliation and orientation of the clay platelets, and the use of a LC polymer forming the organic matrix in between the Laponite particles. Each single feature may be beneficial to increase the materials gas barrier property rendering this composite a promising system with advantageous barrier capacities. In this detailed study, Laponite/LC polymer composite coatings with different clay loadings were investigated regarding their oxygen transmission rate. The obtained gas barrier performance was linked to the quality, respective Laponite content and the underlying composite micro-and nanostructure of the coatings. Most efficient oxygen barrier properties were observed for composite coatings with 83% Laponite loading that exhibit a structure similar to sheet-like nacre. Further on, advantageous mechanical properties of these Laponite/LC polymer composites reported previously give rise to a multifunctional composite system. KW - gas permeation KW - liquid crystal KW - Laponite KW - liquid crystal polymer KW - bio-inspired KW - organic-inorganic composite material KW - self-organization Y1 - 2016 U6 - https://doi.org/10.1088/1748-3190/11/3/035005 SN - 1748-3182 SN - 1748-3190 VL - 11 PB - IOP Publ. Ltd. CY - Bristol ER - TY - JOUR A1 - Secker, Christian A1 - Voelkel, Antje A1 - Tiersch, Brigitte A1 - Koetz, Joachim A1 - Schlaad, Helmut T1 - Thermo-Induced Aggregation and Crystallization of Block Copolypeptoids in Water JF - Macromolecules : a publication of the American Chemical Society N2 - Block copolypeptoids comprising a thermosensitive, crystallizable poly(N-(n-propyl)glycine) block and a watersoluble poly(N-methylglycine) block, P70My (y = 23, 42, 76, 153, and 290), were synthesized bY ring-opening polymerization of the corresponding N-alkylglycine N-carboxyanhydrides (NCAs) and examined according to their thermo-induced aggregation and crystallization in water by turbidimetty, micro-differential scanning calorimetry (micro-DSC); cryogenic scanning electron microscopy (cryo-SEM), analytical ultracentrifugation (AUC), and static light scattering (SLS). At a temperature above the cloud point temperature, the initially formed micellar aggregates started to crystallize and grow into larger complex assemblies of about 100-500 nm, exhibiting flower-like (P70M23), ellipsoidal (P70M42 and P70M72) or irregular shapes (P70M153 and.P70M290). Y1 - 2016 U6 - https://doi.org/10.1021/acs.macromol.5b02481 SN - 0024-9297 SN - 1520-5835 VL - 49 SP - 979 EP - 985 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - Thielke, Michael W. A1 - Secker, Christian A1 - Schlaad, Helmut A1 - Theato, Patrick T1 - Electrospinning of Crystallizable Polypeptoid Fibers JF - Macromolecular rapid communications N2 - A unique fabrication process of low molar mass, crystalline polypeptoid fibers is described. Thermoresponsive fiber mats are prepared by electrospinning a homogeneous blend of semicrystalline poly(N-(n-propyl) glycine) (PPGly; 4.1 kDa) with high molar mass poly(ethylene oxide) (PEO). Annealing of these fibers at approximate to 100 degrees C selectively removes the PEO and produces stable crystalline fiber mats of pure PPGly, which are insoluble in aqueous solution but can be redissolved in methanol or ethanol. The formation of water-stable polypeptoid fiber mats is an important step toward their utilization in biomedical applications such as tissue engineering or wound dressing. KW - biomaterials KW - crystallization KW - electrospinning KW - polypeptoids KW - thermoresponsive Y1 - 2016 U6 - https://doi.org/10.1002/marc.201500502 SN - 1022-1336 SN - 1521-3927 VL - 37 SP - 100 EP - 104 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Doriti, Afroditi A1 - Brosnan, Sarah M. A1 - Weidner, Steffen M. A1 - Schlaad, Helmut T1 - Synthesis of polysarcosine from air and moisture stable N-phenoxycarbonyl-N-methylglycine assisted by tertiary amine base JF - Polymer Chemistry N2 - Polysarcosine (M-n = 3650-20 000 g mol(-1), D similar to 1.1) was synthesized from the air and moisture stable N-phenoxycarbonyl-N-methylglycine. Polymerization was achieved by in situ transformation of the urethane precursor into the corresponding N-methylglycine-N-carboxyanhydride, when in the presence of a non-nucleophilic tertiary amine base and a primary amine initiator. Y1 - 2016 U6 - https://doi.org/10.1039/c6py00221h SN - 1759-9954 SN - 1759-9962 VL - 7 SP - 3067 EP - 3070 PB - Royal Society of Chemistry CY - Cambridge ER - TY - JOUR A1 - Gangloff, Niklas A1 - Ulbricht, Juliane A1 - Lorson, Thomas A1 - Schlaad, Helmut A1 - Luxenhofer, Robert T1 - Peptoids and Polypeptoids at the Frontier of Supra- and Macromolecular Engineering JF - Chemical reviews Y1 - 2016 U6 - https://doi.org/10.1021/acs.chemrev.5b00201 SN - 0009-2665 SN - 1520-6890 VL - 116 SP - 1753 EP - 1802 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - Vacogne, Charlotte D. A1 - Schlaad, Helmut T1 - Controlled ring-opening polymerization of alpha-amino acid N-carboxyanhydrides in the presence of tertiary amines JF - Polymer : the international journal for the science and technology of polymers N2 - The mechanism of the primary ammonium/tertiary amine-mediated ring-opening polymerization of gamma-benzyl-L-glutamate N-carboxyanhydride (BLG-NCA) was investigated. Kinetic analyses revealed that the normal amine mechanism (NAM) together with a dormant-active chain end equilibrium were responsible for the controlled nature of this polymerization pathway, but that the polymerization also proceeded via the activated monomer mechanism (AMM). Mixtures of primary amines (1 equiv) and tertiary amines (0-1.5 equiv) were therefore tested to confirm the co-existence of the NAM and AMM and determine the limits for a controlled polymerization. For tertiary amine molar fractions smaller than 0.8 equiv, the reaction times were greatly reduced (compared to primary amine-initiated polymerization) without compromising the control of the reaction. Hence, the polymerization of NCA can proceed in a controlled manner even when the AMM contributes to the overall chain growth mechanism. (C) 2017 Elsevier Ltd. All rights reserved. KW - Ring-opening polymerization KW - Amino acid N-carboxyanhydride KW - NCA KW - Kinetics KW - Mechanism Y1 - 2017 U6 - https://doi.org/10.1016/j.polymer.2017.07.062 SN - 0032-3861 SN - 1873-2291 VL - 124 SP - 203 EP - 209 PB - Elsevier CY - Oxford ER - TY - JOUR A1 - Dani, Alessandro A1 - Tauber, Karoline A1 - Zhang, Weiyi A1 - Schlaad, Helmut A1 - Yuan, Jiayin T1 - Stable Covalently Photo-Crosslinked Poly(Ionic Liquid) Membrane with Gradient Pore Size JF - Macromolecular rapid communications N2 - Porous polyelectrolyte membranes stable in a highly ionic environment are obtained by covalent crosslinking of an imidazolium-based poly(ionic liquid). The crosslinking reaction involves the UV light-induced thiol-ene (click) chemistry, and the phase separation, occurring during the crosslinking step, generates a fully interconnected porous structure in the membrane. The porosity is on the order of the micrometer scale and the membrane shows a gradient of pore size across the membrane cross-section. The membrane can separate polystyrene latex particles of different size and undergoes actuation in contact with acetone due to the asymmetric porous structure. KW - membrane KW - photo-crosslinked KW - poly(ionic liquid) KW - porous structure Y1 - 2017 U6 - https://doi.org/10.1002/marc.201700167 SN - 1022-1336 SN - 1521-3927 VL - 38 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Wessig, Pablo A1 - Schulze, Tanja A1 - Pfennig, Alexandra A1 - Weidner, Steffen M. A1 - Prentzel, Sascha A1 - Schlaad, Helmut T1 - Thiol-ene polymerization of oligospiroketal rods JF - Polymer Chemistry N2 - The nucleophilic thiol-ene (thia-Michael) reaction between molecular rods bearing terminal thiols and bis-maleimides was investigated. The molecular rods have oligospiroketal (OSK) and oligospirothioketal (OSTK) backbones. Contrary to the expectations, cyclic oligomers were always obtained instead of linear rigid-rod polymers. Replacing the OS(T)K rods with a flexible chain yielded polymeric products, suggesting that the OS(T) K structure is responsible for the formation of cyclic products. The reason for the preferred formation of cyclic products is due to the presence of folded conformations, which have already been described for articulated rods. Y1 - 2017 U6 - https://doi.org/10.1039/c7py01569k SN - 1759-9954 SN - 1759-9962 VL - 8 SP - 6879 EP - 6885 PB - Royal Society of Chemistry CY - Cambridge ER - TY - JOUR A1 - Bogomolova, Anna A1 - Secker, Christian A1 - Koetz, Joachim A1 - Schlaad, Helmut T1 - Thermo-induced multistep assembly of double-hydrophilic block copolypeptoids in water JF - Colloid and polymer science : official journal of the Kolloid-Gesellschaft N2 - The aqueous solution behavior of thermoresponsive-hydrophilic block copolypeptoids, i.e., poly(N-(n-propyl)glycine) (x) -block-poly(N-methylglycine) (y) (x = 70; y = 23, 42, 76), in the temperature range of 20-45 A degrees C is studied. Turbidimetric analyses of the 0.1 wt% aqueous solutions reveal two cloud points at T (cp)similar to 30 and 45 A degrees C and a clearing point in between at T (cl)similar to 42 A degrees C. Temperature-dependent dynamic light scattering (DLS) suggest that right above the first collapse temperature, single polymer molecules assemble into large structures which upon further heating, i.e., at the clearing point temperature, disassemble into micelle-like structures. Upon further heating, the aggregates start to grow again in size, as recognized by the second cloud point, through a crystallization process. KW - Polypeptoids KW - Block copolymers KW - Thermoresponsive KW - Self-assembly Y1 - 2017 U6 - https://doi.org/10.1007/s00396-017-4044-6 SN - 0303-402X SN - 1435-1536 VL - 295 SP - 1305 EP - 1312 PB - Springer CY - New York ER - TY - JOUR A1 - Jain, Varun A1 - Wheeler, Joshua J. A1 - Ess, Daniel H. A1 - Noack, Sebastian A1 - Vacogne, Charlotte D. A1 - Schlaad, Helmut A1 - Bahr, Stephan A1 - Dietrich, Paul A1 - Meyer, Michael A1 - Thissen, Andreas A1 - Linford, Matthew R. T1 - Poly(gamma-benzyl l-glutamate), by near-ambient pressure XPS JF - Surface science spectra : SSS : an international journal & database devoted to archiving spectra from surfaces & interfaces N2 - Near-ambient pressure x-ray photoelectron spectroscopy (NAP-XPS) is a less traditional form of XPS that allows samples to be analyzed at relatively high pressures, i. e., at greater than 2500 Pa. In this study, poly(.- benzyl L- glutamate) (PBLG) with a molar mass of 11.3 kg/mol was analyzed by NAP-XPS; here, we show the survey, C 1s, N 1s, and O 1s narrow scans of PBLG. The C 1s peak envelope was fitted in three different ways, to five, six, or seven synthetic peaks. In each fit, there was also a shake-up signal. The O 1s narrow scan was well fit with three peaks: CZO and CvO in a 1:2 ratio from the polymer, and a higher energy signal from water vapor. Hartree-Fock orbital energies of a model monomer served as a guide to an additional fit of the C 1s envelope. KW - near-ambient pressure x-ray photoelectron spectroscopy KW - NAP-XPS KW - XPS KW - polymer KW - poly(gamma-benzyl L-glutamate) KW - PBLG Y1 - 2019 U6 - https://doi.org/10.1116/1.5109121 SN - 1055-5269 SN - 1520-8575 VL - 26 IS - 2 PB - American Institute of Physics CY - Melville ER - TY - JOUR A1 - Hu, Shuangyan A1 - Zhao, Junpeng A1 - Zhang, Guangzhao A1 - Schlaad, Helmut T1 - Macromolecular architectures through organocatalysis JF - Progress in Polymer Science N2 - In virtue of the rising demand for metal-free polymeric materials, organocatalytic polymerization has emerged and blossomed unprecedentedly in the past 15 years into an appealing research area and a powerful arsenal for polymer synthesis. In addition to the inherent merits as being metal-free, small molecule organocatalysts have also provided opportunities to develop alternative and, in many cases, more expedient synthetic approaches toward macromolecular architectures, that play a crucial role in shaping the properties of the obtained polymers. A majority of preliminary studies exploring for new catalysts, catalytic mechanisms and optimized polymerization conditions are extended to application of the catalytic systems on rational design and controlled synthesis of various macromolecular architectures. Such endeavors are described in this review, categorized by the architectural elements including chain structure (types, sequence and composition of monomeric units constituting the polymer chains), topological structure (the fashion different polymer chains are covalently attached to each other within the macromolecule) and functionality (position and amount of functional groups that endow the entire macromolecule with specific chemical, physico-chemical or biological properties). (C) 2017 Published by Elsevier B.V. KW - Organocatalytic polymerization KW - Metal-free polymerization KW - Macromolecular architecture KW - Controlled polymer synthesis Y1 - 2017 U6 - https://doi.org/10.1016/j.progpolymsci.2017.07.002 SN - 0079-6700 SN - 1873-1619 VL - 74 SP - 34 EP - 77 PB - Elsevier CY - Oxford ER - TY - JOUR A1 - Das, Abhijna A1 - El-Tawargy, Ahmed S. A1 - Khechine, Emna A1 - Noack, Sebastian A1 - Schlaad, Helmut A1 - Reiter, Günter A1 - Reiter, Renate T1 - Controlling Nucleation in Quasi-Two-Dimensional Langmuir Poly(L-lactide) Films through Variation of the Rate of Compression JF - Langmuir N2 - We studied morphological changes in a quasi-two-dimensional Langmuir film of low molar mass poly(L-lactide) upon increasing the surface density, starting from randomly distributed molecules to a homogeneous monolayer of closely packed molecules, followed by nucleation and growth of mesoscopic, three-dimensional clusters from an overcompressed monolayer. The corresponding nucleation density of mesoscopic clusters within the monolayer can be tailored through variation of the rate of compression. For a given surface density and temperature, the nucleation probability was found to increase linearly with the rate of compression, allowing to adjust the density of mesoscopic clusters over nearly 2 orders magnitude. Y1 - 2019 U6 - https://doi.org/10.1021/acs.langmuir.9b00619 SN - 0743-7463 VL - 35 IS - 18 SP - 6129 EP - 6136 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - Behrendt, Felix Nicolas A1 - Hess, Andreas A1 - Lehmann, Max A1 - Schmidt, Bernd A1 - Schlaad, Helmut T1 - Polymerization of cystine-derived monomers JF - Polymer Chemistry N2 - Cystine was used as a platform chemical to prepare cyclic and acyclic monomers for entropy-driven ringopening polymerization (ED-ROMP) via olefin or disulfide metathesis and for step-growth polymerization. The olefin ED-ROMP of an olefin/disulfide containing 16-atom macrocycle using the 3rd generation Grubbs catalyst was examined in greater detail. Kinetic studies revealed that the catalyst turned inactive during the polymerization, which limited the achievable (apparent) polymer molar mass to similar to 70 kg mol(-1). Such limitation could be overcome with the disulfide ED-ROMP of the same macrocycle to yield polymers with molar masses of up to 180 kg mol(-1). The step-growth polymerizations of acyclic diene and dithiol monomers via olefin metathesis or oxidation were far less effective and yielded just low molar mass polymers or oligomers; photopolymerization of a thiol-ene monomer produced a polyester with a molar mass of 35 kg mol(-1). Y1 - 2019 U6 - https://doi.org/10.1039/c9py00118b SN - 1759-9954 SN - 1759-9962 VL - 10 IS - 13 SP - 1636 EP - 1641 PB - Royal Society of Chemistry CY - Cambridge ER - TY - JOUR A1 - Zheng, Botuo A1 - Bai, Tianwen A1 - Tao, Xinfeng A1 - Schlaad, Helmut A1 - Ling, Jun T1 - Identifying the Hydrolysis of Carbonyl Sulfide as a Side Reaction Impeding the Polymerization of N-Substituted Glycine N-Thiocarboxyanhydride JF - Biomacromolecules : an interdisciplinary journal focused at the interface of polymer science and the biological sciences N2 - Polypeptoids are noticeable biological materials due to their versatile properties and various applications in drug delivery, surface modification, self-assembly, etc. N-Substituted glycine N-thiocarboxyanhydrides (NNTAs) are more stable monomers than the corresponding N-carboxyanhydrides (NNCAs) and enable one to prepare polypeptoids via ring-opening polymerization even in the presence of water. However, larger amounts of water (>10,000 ppm) cause inhibition of the polymerization. Herein, we discover that during polymerization hydrogen sulfide evolves from the hydrolysis of carbonyl sulfide, which is the byproduct of ring-opening reaction, and reacts with NNTA to produce cyclic oligopeptoids. The capture of N-ethylethanethioic acid as an intermediate product confirms the reaction mechanism together with density functional theory quantum computational results. By bubbling the polymerization solution with argon, the side reaction can be suppressed to allow the synthesis of polysarcosine with high molar mass (M-n = 11,200 g/mol, D = 1.25) even in the presence of similar to 10,000 ppm of water. Y1 - 2018 U6 - https://doi.org/10.1021/acs.biomac.8b01119 SN - 1525-7797 SN - 1526-4602 VL - 19 IS - 11 SP - 4263 EP - 4269 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - Hardy, John G. A1 - Bertin, Annabelle A1 - Torres-Rendon, Jose Guillermo A1 - Leal-Egana, Aldo A1 - Humenik, Martin A1 - Bauer, Felix A1 - Walther, Andreas A1 - Cölfen, Helmut A1 - Schlaad, Helmut A1 - Scheibel, Thomas R. T1 - Facile photochemical modification of silk protein-based biomaterials JF - Macromolecular bioscience N2 - Silk protein-based materials show promise for application as biomaterials for tissue engineering. The simple and rapid photochemical modification of silk protein-based materials composed of either Bombyx mori silkworm silk or engineered spider silk proteins (eADF4(C16)) is reported. Radicals formed on the silk-based materials initiate the polymerization of monomers (acrylic acid, methacrylic acid, or allylamine) which functionalize the surface of the silk materials with poly(acrylic acid) (PAA), poly(methacrylic acid) (PMAA), or poly(allylamine) (PAAm). To demonstrate potential applications of this type of modification, the polymer-modified silks are mineralized. The PAA- and PMAA-functionalized silks are mineralized with calcium carbonate, whereas the PAAm-functionalized silks are mineralized with silica, both of which provide a coating on the materials that may be useful for bone tissue engineering, which will be the subject of future investigations. KW - biomaterials KW - chemical modification KW - photochemistry KW - silkworm silk KW - spider silk Y1 - 2018 U6 - https://doi.org/10.1002/mabi.201800216 SN - 1616-5187 SN - 1616-5195 VL - 18 IS - 11 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Lüdecke, Nils A1 - Weidner, Steffen M. A1 - Schlaad, Helmut T1 - Poly(2-oxazoline)s Based on Phenolic Acids JF - Macromolecular rapid communications N2 - A series of phenolic-acid-based 2-oxazoline monomers with methoxy-substituted phenyl and cinnamyl side chains is synthesized and polymerized in a microwave reactor at 140 °C using methyl tosylate as the initiator. The obtained poly(2-oxazoline)s are characterized by NMR spectroscopy, MALDI-TOF mass spectrometry, and size-exclusion chromatography (SEC). Kinetic studies reveal that the microwave-assisted polymerization is fast and completed within less than ≈10 min for low monomer-to-initiator ratios of ≤25. Polymers with number-average molar masses of up to 6500 g mol−1 and low dispersity (1.2–1.3) are produced. The aryl methyl ethers are successfully cleaved with aluminum triiodide/N,N′-diisopropylcarbodiimide to give a poly(2-oxazoline) with pendent catechol groups. KW - 2-oxazoline KW - catechol KW - cationic ring-opening polymerization KW - microwave KW - phenolic acid Y1 - 2019 U6 - https://doi.org/10.1002/marc.201900404 SN - 1022-1336 SN - 1521-3927 VL - 41 IS - 1 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Noack, Sebastian A1 - Schanzenbach, Dirk A1 - Koetz, Joachim A1 - Schlaad, Helmut T1 - Polylactide-based amphiphilic block copolymers BT - Crystallization-Induced Self-Assembly and Stereocomplexation JF - Macromolecular rapid communications N2 - The aqueous self-assembly behavior of a series of poly(ethylene glycol)-poly(l-/d-lactide) block copolymers and corresponding stereocomplexes is examined by differential scanning calorimetry, dynamic light scattering, and transmission electron microscopy. Block copolymers assemble into spherical micelles and worm-like aggregates at room temperature, whereby the fraction of the latter seemingly increases with decreasing lactide weight fraction or hydrophobicity. The formation of the worm-like aggregates arises from the crystallization of the polylactide by which the spherical micelles become colloidally unstable and fuse epitaxically with other micelles. The self-assembly behavior of the stereocomplex aggregates is found to be different from that of the block copolymers, resulting in rather irregular-shaped clusters of spherical micelles and pearl-necklace-like structures. KW - crystallization KW - polylactide KW - self-assembly KW - stereocomplexation Y1 - 2018 U6 - https://doi.org/10.1002/marc.201800639 SN - 1022-1336 SN - 1521-3927 VL - 40 IS - 1 PB - Wiley-VCH CY - Weinheim ER - TY - CHAP A1 - Schlaad, Helmut A1 - Luedecke, Nils T1 - Bio-sourced chelating poly(2-oxazoline)s T2 - Abstracts of papers : joint conference / The Chemical Institute of Cananda, CIC, American Chemical Society, ACS Y1 - 2019 SN - 0065-7727 VL - 257 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - Vacogne, Charlotte Dominique A1 - Wei, Chunxiang A1 - Tauer, Klaus A1 - Schlaad, Helmut T1 - Self-assembly of alpha-helical polypeptides into microscopic and enantiomorphic spirals JF - Journal of the american chemical society N2 - Helical structures are ubiquitous in biological materials and often serve a structural purpose. Bioinspired helical materials can be challenging to synthesize and rarely reach the degree of hierarchy of their natural counterparts. Here we report the first example of particles synthesized by direct emulsification of polypeptides found to display spiral morphologies in the dry state. The polypeptides were alpha-helical homo- and copolypeptides of gamma-benzyl glutamate and allylglycine. The chirality of the spirals was controlled by the chirality of the alpha-helices. Notably, right-handed alpha-helical polypeptides (rich in 1, residues) produced clockwise spirals, whereas left-handed alpha-helical polypeptides (rich in D residues) produced the enantiomorphs, i.e., counterclockwise spirals. The disruption of the alpha-helical conformation by the introduction of chiral defects led to less regular spirals and in some cases their suppression. A hypothesis for the transmission of helicity and chirality from a molecular to a higher hierarchical level, involving fibril bundling of coiled alpha-helices, is proposed. Y1 - 2018 U6 - https://doi.org/10.1021/jacs.8b06503 SN - 0002-7863 VL - 140 IS - 36 SP - 11387 EP - 11394 PB - American Chemical Society CY - Washington ER - TY - GEN A1 - Dani, Alessandro A1 - Taeuber, Karoline A1 - Zhang, Weiyi A1 - Schlaad, Helmut A1 - Yuan, Jiayin T1 - Stable covalently photo-cross-linked porous poly(ionic liquid) membrane with gradient pore size T2 - Abstracts of papers : joint conference / The Chemical Institute of Cananda, CIC, American Chemical Society, ACS N2 - Porous polyelectrolyte membranes stable in a highly ionic environment are obtained by covalent crosslinking of an imidazolium-based poly(ionic liquid). The crosslinking reaction involves the UV light-induced thiol-ene (click) chemistry, and the phase separation, occurring during the crosslinking step, generates a fully interconnected porous structure in the membrane. The porosity is on the order of the micrometer scale and the membrane shows a gradient of pore size across the membrane cross-section. The membrane can separate polystyrene latex particles of different size and undergoes actuation in contact with acetone due to the asymmetric porous structure. Y1 - 2018 SN - 0065-7727 VL - 256 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - Matic, Aleksandar A1 - Schlaad, Helmut T1 - Thiol-ene photofunctionalization of 1,4-polymyrcene JF - Polymer international N2 - 1,4-Polymyrcene was synthesized by anionic polymerization of -myrcene and was subjected to photochemical functionalization with various thiols (i.e. methyl thioglycolate, methyl 3-mercaptopropionate, butyl 3-mercaptopropionate, ethyl 2-mercaptopropionate and 2-methyl-2-propanethiol) using benzophenone/UV light as the radical source. The yield of thiol addition to the trisubstituted double bonds of 1,4-polymyrcene decreased in the order 1 degrees thiol (ca 95%) > 2 degrees thiol (ca 80%) > 3 degrees thiol (<5%), due to the reversibility of the thiol-ene reaction. Remarkably, thiol addition to the side-chain double bonds was 8 - 10 times (1 degrees thiol) or 24 times (2 degrees thiol) faster than to the main-chain double bonds, which can be explained by the different accessibility of the double bonds and steric hindrance. Despite the use of a 10-fold excess of thiol with respect to myrcene units, the thiol-ene addition was accompanied by chain coupling reactions, which in the extreme case of 3 degrees thiol (or in the absence of thiol) resulted in the formation of insoluble crosslinked material. As an example, a methyl-thioglycolate-functionalized 1,4-polymyrcene was saponified/crosslinked to give submicron polyelectrolyte particles in dilute alkaline solution. (c) 2018 Society of Chemical Industry KW - polymyrcene KW - thiol-ene KW - photochemistry KW - regioselectivity Y1 - 2018 U6 - https://doi.org/10.1002/pi.5534 SN - 0959-8103 SN - 1097-0126 VL - 67 IS - 5 SP - 500 EP - 505 PB - Wiley CY - Hoboken ER - TY - JOUR A1 - Chen, Ye A1 - Song, Qilei A1 - Zhao, Junpeng A1 - Gong, Xiangjun A1 - Schlaad, Helmut A1 - Zhang, Guangzhao T1 - Betulin-Constituted multiblock amphiphiles for broad-spectrum protein resistance JF - ACS applied materials & interfaces N2 - Multiblock-like amphiphilic polyurethanes constituted by poly(ethylene oxide) and biosourced betulin are designed for antifouling and synthesized by a convenient organocatalytic route comprising tandem chain-growth and step-growth polymerizations. The doping density of betulin (D-B) in the polymer chain structure is readily varied by a mixed-initiator strategy. The spin-coated polymer films exhibit unique nanophase separation and protein resistance behaviors. Higher D-B leads to enhanced surface hydrophobicity and, unexpectedly, improved protein resistance. It is found that the surface holds molecular-level heterogeneity when D-B is substantially high due to restricted phase separation; therefore, broad-spectrum protein resistance is achieved despite considerable surface hydrophobicity. As D-B decreases, the distance between adjacent betulin units increases so that hydrophobic nanodomains are formed, which provide enough landing areas for relatively small-sized proteins to adsorb on the surface. KW - amphiphilic surface KW - antifouling KW - multiblock copolymer KW - organocatalytic polymerization KW - renewable resource Y1 - 2018 U6 - https://doi.org/10.1021/acsami.7b16255 SN - 1944-8244 VL - 10 IS - 7 SP - 6593 EP - 6600 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - Behrendt, Felix Nicolas A1 - Schlaad, Helmut T1 - Entropy-Driven Ring-Opening Disulfide Metathesis Polymerization for the Synthesis of Functional Poly(disulfide)s JF - Macromolecular rapid communications N2 - Metal-free entropy-driven disulfide metathesis polymerization of unsaturated L-cystine based macrocycles produces high-molar-mass heterofunctional poly(disulfide)s, i.e., poly(ester-disulfide-alkene) and poly(amide-disulfide-alkene); M-w(app) = 44-60 kDa, (sic) > 1.7. The polymerization is fast and reaches equilibrium within 1-5 minutes (monomer conversion 70-90%) in polar aprotic solvents such as N,N-dimethylacetamide, dimethylsulfoxide, or y-valerolactone. Thiol-terminated polymers are stable in bulk or when dissolved in weakly polar solvents, but rapidly depolymerize in dilute polar solution. KW - disulfide KW - macrocycles KW - metathesis KW - ring-opening polymerization Y1 - 2018 U6 - https://doi.org/10.1002/marc.201700735 SN - 1022-1336 SN - 1521-3927 VL - 39 IS - 6 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Behrendt, Felix Nicolas A1 - Schlaad, Helmut T1 - Metathesis polymerization of cystine-based macrocycles JF - Polymer Chemistry N2 - Macrocycles based on L-cystine were synthesized by ring-closing metathesis (RCM) and subsequently polymerized by entropy-driven ring-opening metathesis polymerization (ED-ROMP). Monomer conversion reached similar to 80% in equilibrium and the produced poly (ester-amine-disulfide-alkene)s exhibited apparent molar masses (M-w(app)) of up to 80 kDa and dispersities (D) of similar to 2. The polymers can be further functionalized with acid anhydrides and degraded by reductive cleavage of the main-chain disulfide. Y1 - 2016 U6 - https://doi.org/10.1039/c6py01864e SN - 1759-9954 SN - 1759-9962 VL - 8 IS - 2 SP - 366 EP - 369 PB - Royal Society of Chemistry CY - Cambridge ER - TY - JOUR A1 - Hoogenboom, Richard A1 - Schlaad, Helmut T1 - Thermoresponsive poly(2-oxazoline)s, polypeptoids, and polypeptides JF - Polymer Chemistry N2 - This review covers the recent advances in the emerging field of thermoresponsive polyamides or polymeric amides, i.e., poly(2-oxazoline)s, polypeptoids, and polypeptides, with a specific focus on structure-thermoresponsive property relationships, self-assembly, and applications. Y1 - 2016 U6 - https://doi.org/10.1039/c6py01320a SN - 1759-9954 SN - 1759-9962 VL - 8 IS - 1 SP - 24 EP - 40 PB - Royal Society of Chemistry CY - Cambridge ER - TY - JOUR A1 - Dev, Akhil A1 - Rösler, Alexander A1 - Schlaad, Helmut T1 - Limonene as a renewable unsaturated hydrocarbon solvent for living anionic polymerization of β-myrcene JF - Polymer chemistry N2 - The acyclic monoterpene beta-myrcene is polymerized by anionic polymerization at room temperature using sec-butyllithium as the initiator and the cyclic monoterpene DL-limonene as an unsaturated hydrocarbon solvent. The polymerization is a living process and allows production of polymyrcenes with narrow molar mass distribution ((sic) similar to 1.06) and high content of 1,4 units (similar to 90%) as well as block copolymers. Y1 - 2021 U6 - https://doi.org/10.1039/d1py00570g SN - 1759-9954 SN - 1759-9962 VL - 12 IS - 21 SP - 3084 EP - 3087 PB - Royal Society of Chemistry CY - Cambridge ER - TY - JOUR A1 - Lüdecke, Nils A1 - Schlaad, Helmut T1 - Inspired by mussel adhesive protein BT - hydrophilic cationic copoly(2-oxazoline)s carrying catecholic side chains JF - Polymer Chemistry N2 - A set of new functionalized poly(2-oxazoline) homopolymers and copolymers carrying protected catecholic side chains were prepared by microwave-assisted cationic ring-opening (co)polymerization. The copolymerizations of 2-ethyl-2-oxazoline with either 2-(3,4-dimethoxyphenyl)-, 2-(3,4-dimethoxybenzyl)-, or 2-(3,4-dimethoxycinnamyl)-2-oxazoline (comonomer ratio 90 : 10) produced gradient or random copolymers with narrow molar mass distributions. During the copolymerization with the 2-(3,4-dimethoxycinnamyl)-2-oxazoline, however, chain coupling reactions occurred at monomer conversions of >50%, supposedly via Michael-type addition of intermediately formed ketene N,O-acetal end groups to 3,4-dimethoxycinnamyl amide side chains. A poly[(2-ethyl-2-oxazoline)-grad-(2-(3,4-dimethoxyphenyl)-2-oxazoline)] was examplarily subjected to partial demethylation and acidic hydrolysis to give a hydrophilic copolymer carrying both catecholic and cationic units, which is designed as a bioinspired adhesive copolymer mimicking mussel adhesive protein. Y1 - 2021 U6 - https://doi.org/10.1039/d1py00679g SN - 1759-9962 VL - 12 IS - 37 SP - 5310 EP - 5319 PB - Royal Society of Chemistry CY - Cambridge ER - TY - JOUR A1 - Glatzel, Julia A1 - Noack, Sebastian A1 - Schanzenbach, Dirk A1 - Schlaad, Helmut T1 - Anionic polymerization of dienes in ‘green’ solvents JF - Polymer international N2 - Isoprene and beta-myrcene were polymerized by anionic polymerization in bulk and in the 'green' ether solvents cyclopentyl methyl ether and 2-methyltetrahydrofuran and, for comparison, in cyclohexane and tetrahydrofuran. The polydienes produced in bulk and in cyclohexane contained high amounts of 1,4 units (>90%) whereas those produced in ether solvents were rich in 1,2 and 3,4 units (36%-86%). Comparison of the microstructures and glass transition temperatures of the polydienes obtained in the various solvents suggests that conventionally used solvents can be substituted by environmentally more friendly alternatives. KW - isoprene KW - β‐myrcene KW - anionic polymerization KW - green KW - solvents KW - microstructure KW - glass transition Y1 - 2020 U6 - https://doi.org/10.1002/pi.6152 SN - 0959-8103 SN - 1097-0126 VL - 70 IS - 2 SP - 181 EP - 184 PB - Wiley CY - Hoboken ER - TY - JOUR A1 - Matic, Aleksandar A1 - Hess, Andreas A1 - Schanzenbach, Dirk A1 - Schlaad, Helmut T1 - Epoxidized 1,4-polymyrcene JF - Polymer chemistry N2 - 1,4-Polymyrcene was synthesized by anionic polymerization and epoxidized using meta-chloroperbenzoic acid. Samples with different degrees of epoxidation (25%, 49%, 74%, and 98%) were prepared and examined according to their chemical and thermal properties. Epoxidation was found to increase the glass transition temperature (T-g = 14 degrees C for the 98% epoxidized 1,4-polymyrcene) as well as the shelf live (>10 months). The trisubstituted epoxide groups were remarkably stable against nucleophiles under basic conditions but cross-linked or hydrolyzed in the presence of an acid. Also, highly epoxidized 1,4-polymyrcene readily cross-linked upon annealing at 260 degrees C to produce an epoxy resin. KW - comb poly(beta-myrcene)-graft-poly(l-lactide) copolymers KW - thermoplastic elastomer synthesis KW - myrcen KW - polymerization KW - epoxidation Y1 - 2020 U6 - https://doi.org/10.1039/c9py01783f SN - 1759-9954 SN - 1759-9962 VL - 11 IS - 7 SP - 1364 EP - 1368 PB - Royal Society of Chemistry CY - Cambridge ER - TY - JOUR A1 - Das, Abhijna A1 - Noack, Sebastian A1 - Schlaad, Helmut A1 - Reiter, Günter A1 - Reiter, Renate T1 - Exploring pathways to equilibrate Langmuir polymer films JF - Langmuir N2 - Focusing on the phase-coexistence region in Langmuir films of poly(L-lactide), we investigated changes in nonequilibrated morphologies and the corresponding features of the isotherms induced by different experimental pathways of lateral compression and expansion. In this coexistence region, the surface pressure II was larger than the expected equilibrium value and was found to increase upon compression, i.e., exhibited a nonhorizontal plateau. As shown earlier by using microscopic techniques [Langmuir 2019, 35, 6129-6136], in this plateau region, well-ordered mesoscopic clusters coexisted with a surrounding matrix phase. We succeeded in reducing Pi either by slowing down the rate of compression or through increasing the waiting time after stopping the movement of the barriers, which allowed for relaxations in the coexistence region. Intriguingly, the most significant pressure reduction was observed when recompressing a film that had already been compressed and expanded, if the recompression was started from an area value smaller than the one anticipated for the onset of the coexistence region. This observation suggests a "self-seeding" behavior, i.e., pre-existing nuclei allowed to circumvent the nucleation step. The decrease in Pi was accompanied by a transformation of the initially formed metastable mesoscopic clusters into a thermodynamically favored filamentary morphology. Our results demonstrate that it is practically impossible to obtain fully equilibrated coexisting phases in a Langmuir polymer film, neither under conditions of extremely slow continuous compression nor for long waiting times at a constant area in the coexistence region which allow for reorganization. Y1 - 2020 U6 - https://doi.org/10.1021/acs.langmuir.0c01268 SN - 0743-7463 VL - 36 IS - 28 SP - 8184 EP - 8192 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - Hess, Andreas A1 - Schmidt, Bernhard Volkmar Konrad Jakob A1 - Schlaad, Helmut T1 - Aminolysis induced functionalization of (RAFT) polymer-dithioester with thiols and disulfides JF - Polymer Chemistry N2 - A series of polystyrene- and poly(methyl methacrylate)-dithioesters was subjected to aminolysis under ambient atmospheric conditions, i.e., in the presence of oxygen. Polymer disulfide coupling by oxidation occurred within tens of minutes and the yield of disulfide-coupled polymer increased with decreasing polymer molar mass. Oxidation of thiolates is usually an unwanted side reaction, here it is employed to obtain exclusively polymeric mixed disulfides through in situ aminolysis/functionalization in the presence of a thiol. The in situ aminolysis/functionalization in the presence of a disulfide, Ellman's reagent or polymer disulfide, resulted in the exclusive formation of polymer-dithionitrobenzoic acid, which can be further reacted with a thiol to exchange the terminal functionality, or block copolymer with dynamic disulfide linker, respectively. Y1 - 2020 U6 - https://doi.org/10.1039/d0py01365j SN - 1759-9954 SN - 1759-9962 VL - 11 IS - 48 SP - 7677 EP - 7684 PB - Royal Society of Chemistry CY - Cambridge ER - TY - JOUR A1 - Raju, Rajarshi Roy A1 - Liebig, Ferenc A1 - Hess, Andreas A1 - Schlaad, Helmut A1 - Koetz, Joachim T1 - Temperature-triggered reversible breakdown of polymer-stabilized olive BT - silicone oil Janus emulsions JF - RSC Advances N2 - A one-step moderate energy vibrational emulsification method was successfully employed to produce thermo-responsive olive/silicone-based Janus emulsions stabilized by poly(N,N-diethylacrylamide) carrying 0.7 mol% oleoyl side chains. Completely engulfed emulsion droplets remained stable at room temperature and could be destabilized on demand upon heating to the transition temperature of the polymeric stabilizer. Time-dependent light micrographs demonstrate the temperature-induced breakdown of the Janus droplets, which opens new aspects of application, for instance in biocatalysis. KW - microgels KW - step Y1 - 2019 U6 - https://doi.org/10.1039/c9ra03463c SN - 2046-2069 VL - 9 IS - 35 SP - 19271 EP - 19277 PB - RSC Publishing CY - London ER - TY - JOUR A1 - Diehl, Christina A1 - Cernoch, Peter A1 - Zenke, Ingrid A1 - Runge, Heike A1 - Pitschke, Rona A1 - Hartmann, Juergen A1 - Tiersch, Brigitte A1 - Schlaad, Helmut T1 - Mechanistic study of the phase separation/crystallization process of poly(2-isopropyl-2-oxazoline) in hot water N2 - The kinetics of the crystallization of thermoresponsive poly(2-isopropyl-2-oxazoline) in water and the time- dependent evolution of the morphology were examined using wide-angle X-ray scattering and conventional and cryogenic scanning electron microscopy. Results indicate that a temperature-induced phase separation produces a bicontinuous polymer network-like structure, which with the onset of crystallization collapses into individual particles (1-2 mu m in diameter) composed of a porous fiber mesh. Nanofibers then preferentially form at the particle surface, thus wrapping the microspheres like a ball of wool. The particle morphology is severely affected by changes in temperature and less by the initial polymer concentration. Y1 - 2010 UR - http://www.rsc.org/Publishing/Journals/sm/index.asp U6 - https://doi.org/10.1039/C0sm00114g SN - 1744-683X ER - TY - THES A1 - Schlaad, Helmut T1 - Polymer self-assembly : adding complexity to mesostructures of diblock copolymers by specific interactions N2 - In dieser Arbeit wurde die Rolle selektiver, nicht-kovalenter Wechselwirkungen bei der Selbstorganisation von Diblockcopolymeren untersucht. Durch Einführung elektrostatischer, dipolarer Wechselwirkungen oder Wasserstoffbrückenbindungen sollte es gelingen, komplexe Mesostrukturen zu erzeugen und die Ordnung vom Nanometerbereich auf größere Längenskalen auszuweiten. Diese Arbeit ist im Rahmen von Biomimetik zu sehen, da sie Konzepte der synthetischen Polymer- und Kolloidchemie und Grundprinzipien der Strukturbildung in supramolekularen und biologischen Systemen verbindet. Folgende Copolymersysteme wurden untersucht: (i) Blockionomere, (ii) Blockcopolymere mit chelatisierenden Acetoacetoxyeinheiten und (iii) Polypeptid-Blockcopolymere. N2 - In this work, the basic principles of self-organization of diblock copolymers having the in¬herent property of selective or specific non-covalent binding were examined. By the introduction of electrostatic, dipole–dipole, or hydrogen bonding interactions, it was hoped to add complexity to the self-assembled mesostructures and to extend the level of ordering from the nanometer to a larger length scale. This work may be seen in the framework of biomimetics, as it combines features of synthetic polymer and colloid chemistry with basic concepts of structure formation applying in supramolecular and biological systems. The copolymer systems under study were (i) block ionomers, (ii) block copolymers with acetoacetoxy chelating units, and (iii) polypeptide block copolymers. T2 - Polymer self-assembly : adding complexity to mesostructures of diblock copolymers by specific interactions KW - block copolymer KW - polypeptide KW - controlled polymerization KW - self-assembly KW - specific interactions KW - micelle KW - vesicle KW - solid-state structure KW - colloids KW - Blockcopolymer KW - Polypeptid KW - kontrollierte Polymerisation KW - Selbstorganisation KW - spezifische Wechselwirkungen KW - Mizelle KW - Vesikel KW - Festkörperstruktur KW - Kol Y1 - 2005 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-0001824 ER - TY - JOUR A1 - Al-Naji, Majd A1 - Schlaad, Helmut A1 - Antonietti, Markus T1 - New (and old) monomers from biorefineries to make polymer chemistry more sustainable JF - Macromolecular rapid communications N2 - This opinion article describes recent approaches to use the "biorefinery" concept to lower the carbon footprint of typical mass polymers, by replacing parts of the fossil monomers with similar or even the same monomer made from regrowing dendritic biomass. Herein, the new and green catalytic synthetic routes are for lactic acid (LA), isosorbide (IS), 2,5-furandicarboxylic acid (FDCA), and p-xylene (pXL). Furthermore, the synthesis of two unconventional lignocellulosic biomass derivable monomers, i.e., alpha-methylene-gamma-valerolactone (MeGVL) and levoglucosenol (LG), are presented. All those have the potential to enter in a cost-effective way, also the mass market and thereby recover lost areas for polymer materials. The differences of catalytic unit operations of the biorefinery are also discussed and the challenges that must be addressed along the synthesis path of each monomers. KW - biodegradable polymers KW - biorefineries KW - carbohydrate‐ based KW - monomers KW - green polymers KW - lignocellulosic biomass Y1 - 2020 U6 - https://doi.org/10.1002/marc.202000485 SN - 1022-1336 SN - 1521-3927 VL - 42 IS - 3 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Debsharma, Tapas A1 - Schmidt, Bernd A1 - Laschewsky, Andre A1 - Schlaad, Helmut T1 - Ring-opening metathesis polymerization of unsaturated carbohydrate derivatives BT - levoglucosenyl alkyl ethers JF - Macromolecules : a publication of the American Chemical Society N2 - A series of biomass-derived levoglucosenyl alkyl ethers (alkyl = methyl, ethyl, n-propyl, isopropyl, and n-butyl) were synthesized and polymerized by ring-opening olefin metathesis polymerization using the Grubbs catalyst C793 at room temperature. Polymerizations were successfully performed in conventional solvents such as 1,4-dioxane and dichloromethane as well as in polar aprotic "green" solvents such as 2-methyltetrahydrofuran, dihydrolevoglucosenone (Cyrene), and ethyl acetate. The prepared polyacetals with degrees of polymerization of similar to 100 exhibit Schulz-Flory-type molar mass distributions and are thermoplastic materials with rather low glass transition temperatures in the range of 43-0 degrees C depending on the length of the alkyl substituent. Kinetic studies revealed that the polymerization proceeded rapidly to a steady state with a certain minimum monomer concentration threshold. When the steady state was reached, just about half of the [Ru] catalyst had been effective to initiate the polymerization, indicating that the initiation step was a slow process. The remaining catalyst was still active and did no longer react with monomers but with in-chain double bonds, cutting the formed polymer chains into shorter fragments. In the long term, all catalyst was consumed and propagating [Ru] chain ends were deactivated by the elimination of [Ru] from the chain ends to form inactive chains with terminal aldehyde groups. Y1 - 2021 U6 - https://doi.org/10.1021/acs.macromol.0c02821 SN - 0024-9297 SN - 1520-5835 VL - 54 IS - 6 SP - 2720 EP - 2728 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - Goldhahn, Christian A1 - Schubert, Jonas A1 - Schlaad, Helmut A1 - Ferri, James K. A1 - Fery, Andreas A1 - Chanana, Munish T1 - Synthesis of Metal@Protein@Polymer Nanoparticles with Distinct Interfacial and Phase Transfer Behavior JF - Chemistry of materials : a publication of the American Chemical Society N2 - In this study, we present a novel and facile method for the synthesis of multiresponsive plasmonic nanoparticles with an interesting interfacial behavior. We used thiol-initiated photopolymerization technique to graft poly(N-isopropylacrylamide) onto the surface of protein-coated gold nanoparticles. The combination of the protein bovine serum albumin with the thermoresponsive polymer leads to smart hybrid nanoparticles, which show a stimuli-responsive behavior of their aggregation and a precisely controllable phase transfer behavior. Three interconnected stimuli, namely, temperature, ionic strength, and pH, were identified as property tuning switches. The aggregation was completely reversible and was quantified by determining Smoluchowski’s instability ratios with time-resolved dynamic light scattering. The tunable hydrophobicity via the three stimuli was used to study interfacial activity and phase transfer behavior of the nanoparticles at an octanol/water interface. Depending on the type of coating (i.e., protein or protein/polymer) as well as the three external stimuli, the nanoparticles either remained in the aqueous phase (aggregated or nonaggregated), accumulated at the oil/water interface, wet the glass wall between the glass vial and the octanol phase, or even crossed the oil/water interface. Such smart and interfacially active nanoparticles with external triggers that are capable of crossing oil/water interfaces under physiological conditions open up new avenues for a variety of applications ranging from the development of drug-delivery nanosystems across biological barriers to the preparation of new catalytic materials. Y1 - 2018 U6 - https://doi.org/10.1021/acs.chemmater.8b02314 SN - 0897-4756 SN - 1520-5002 VL - 30 IS - 19 SP - 6717 EP - 6727 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - Patel, Dhananjay I. A1 - Noack, Sebastian A1 - Vacogne, Charlotte D. A1 - Schlaad, Helmut A1 - Bahr, Stephan A1 - Dietrich, Paul A1 - Meyer, Michael A1 - Thissen, Andreas A1 - Linford, Matthew R. T1 - Poly(L-lactic acid), by near-ambient pressure XPS JF - Surface Science Spectra N2 - Near ambient pressure - x-ray photoelectron spectroscopy (NAP-XPS) is a less traditional form of XPS that allows samples to be analyzed at relatively high pressures, i.e., at 2500Pa or higher. With NAP-XPS, one can analyze moderately volatile liquids, biological samples, porous materials, and/or polymeric materials that outgas significantly. In this submission we show C 1s, O 1s, and survey NAP-XPS spectra from poly(L-lactic acid). The C 1s and O 1s envelopes were fit with three and two Gaussian-Lorentzian sum functions, respectively. Water vapor (800Pa) was used as the residual gas for charge compensation, which was confirmed by the sharp peak at 535.0 eV in the O 1s narrow scan. The uniqueness plot corresponding to the C 1s fit shows that the fit parameters had statistical significance. C 1s and O 1s spectra of PLLA damaged by exposure to x-rays for ca. 1 hour are also included. Published by the AVS. KW - near-ambient pressure X-ray photoelectron spectroscopy KW - NAP-XPS KW - XPS KW - Water Vapor Y1 - 2019 U6 - https://doi.org/10.1116/1.5110309 SN - 1055-5269 SN - 1520-8575 VL - 26 IS - 2 PB - American Institute of Physics CY - Melville ER - TY - JOUR A1 - Keckeis, Philipp A1 - Zeller, Enriko A1 - Jung, Carina A1 - Besirske, Patricia A1 - Kirner, Felizitas A1 - Ruiz-Agudo, Cristina A1 - Schlaad, Helmut A1 - Cölfen, Helmut T1 - Modular toolkit of multifunctional block copoly(2-oxazoline)s for the synthesis of nanoparticles JF - Chemistry - a European journal N2 - Post-polymerization modification provides an elegant way to introduce chemical functionalities onto macromolecules to produce tailor-made materials with superior properties. This concept was adapted to well-defined block copolymers of the poly(2-oxazoline) family and demonstrated the large potential of these macromolecules as universal toolkit for numerous applications. Triblock copolymers with separated water-soluble, alkyne- and alkene-containing segments were synthesized and orthogonally modified with various low-molecular weight functional molecules by copper(I)-catalyzed azide-alkyne cycloaddition (CuAAC) and thiol-ene (TE) click reactions, respectively. Representative toolkit polymers were used for the synthesis of gold, iron oxide and silica nanoparticles. KW - block copolymers KW - click chemistry KW - nanoparticles KW - ring-opening KW - polymerization KW - surfactants Y1 - 2021 U6 - https://doi.org/10.1002/chem.202101327 SN - 0947-6539 SN - 1521-3765 VL - 27 IS - 32 SP - 8283 EP - 8287 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Doriti, Afroditi A1 - Brosnan, Sarah M. A1 - Weidner, Steffen M. A1 - Schlaad, Helmut T1 - Synthesis of polysarcosine from air and moisture stable N-phenoxycarbonyl-N-methylglycine assisted by tertiary amine base JF - Polymer Chemistry N2 - Polysarcosine (Mn = 3650–20 000 g mol−1, Đ ∼ 1.1) was synthesized from the air and moisture stable N-phenoxycarbonyl-N-methylglycine. Polymerization was achieved by in situ transformation of the urethane precursor into the corresponding N-methylglycine-N-carboxyanhydride, when in the presence of a non-nucleophilic tertiary amine base and a primary amine initiator. KW - ring-opening polymerization KW - activated urethane derivatives KW - phosgene-free synthesis KW - carboxyanhydrides KW - polypeptides KW - acids KW - copolymers Y1 - 2016 U6 - https://doi.org/10.1039/C6PY00221H SN - 1759-9954 SN - 1759-9962 VL - 7 SP - 3067 EP - 3070 PB - RSC Publ. CY - Cambridge ER - TY - JOUR A1 - Gress, Anja A1 - Heilig, Anne A1 - Smarsly, Bernd M. A1 - Heydenreich, Matthias A1 - Schlaad, Helmut T1 - Hydrogen-bonded polymer nanotubes in water N2 - Intermolecular hydrogen bonding, not hydrophobic interaction, is the driving force for the spontaneous self- assembly of glycosylated polyoxazoline chains into nanotubes in dilute aqueous solution. The structural information is encoded in the relatively simple molecular structure of chains consisting of a tertiary polyamide backbone (hydrogen- accepting) and glucose side chains (hydrogen-donating). The formation of the nanotubes should occur through bending and closing of a 2D hydrogen-bonded layer of interdigitated polymer chains. Y1 - 2009 UR - http://pubs.acs.org/loi/mamobx U6 - https://doi.org/10.1021/Ma900227t SN - 0024-9297 ER - TY - JOUR A1 - Schlaad, Helmut A1 - You, Liangchen A1 - Sigel, Reinhard A1 - Smarsly, Bernd A1 - Heydenreich, Matthias A1 - Mantion, Alexandre A1 - Masic, Admir T1 - Glycopolymer vesicles with an asymmetric membrane N2 - Direct dissolution of glycosylated polybutadiene-poly(ethylene oxide) block copolymers can lead to the spontaneous formation of vesicles or membranes, which on the outside are coated with glucose and on the inside with poly(ethylene oxide). Y1 - 2009 UR - http://www.rsc.org/ej/CC/2009/b820887e.pdf U6 - https://doi.org/10.1039/B820887e SN - 1359-7345 ER - TY - JOUR A1 - Tritschler, Ulrich A1 - Zlotnikov, Igor A1 - Keckeis, Philipp A1 - Schlaad, Helmut A1 - Cölfen, Helmut T1 - Optical properties of self-organized gold nanorod-polymer hybrid films JF - Langmuir N2 - High fractions of gold nanorods were locally aligned by means of a polymeric liquid crystalline phase. The gold nanorods constituting >80 wt % of the thin organic-inorganic composite films form a network with side-by-side and end-to-end combinations. Organization into these network structures was induced by shearing gold nanorod-LC polymer dispersions via spin-coating. The LC polymer is a polyoxazoline functionalized with pendent cholesteryl and carboxyl side groups enabling the polymer to bind to the CTAB stabilizer layer of the gold nanorods via electrostatic interactions, thus forming the glue between organic and inorganic components, and to form a chiral nematic lyotropic phase. The self-assembled locally oriented gold nanorod structuring enables control over collective optical properties due to plasmon resonance coupling, reminiscent of enhanced optical properties of natural biomaterials. Y1 - 2014 U6 - https://doi.org/10.1021/la503507u SN - 0743-7463 VL - 30 IS - 46 SP - 13781 EP - 13790 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - Fuehrer, Felix N. A1 - Schlaad, Helmut T1 - ADMET polymerization of amino-acid-based diene JF - Macromolecular chemistry and physics N2 - 1,4-Di(homo)allyl-2,5-diketopiperazines are synthesized and polymerized via ADMET using the Hoveyda-Grubbs 2nd generation catalyst. The but-3-enylated diketopiperazine can be converted into unsaturated tertiary polyamide with molar mass of <3000 g mol(-1), whereas the allylated diketopiperazine cannot. Double-bond isomerization occurs regardless of whether or not benzoquinone is present. A polyesteramide with a higher molar mass of ca. 4800 g mol(-1) is obtained by the alternating copolymerization (ALTMET) of 1,4-di(but-3-enyl)-2,5-di ketopiperazine and ethylene glycol diacrylate. A post-polymerization modification of the poly(ester)amides via radical thiol-ene chemistry, however, fails. KW - acyclic diene metathesis (ADMET) polymerization KW - amino acids KW - diketopiperazine KW - metathesis KW - step-growth polymerization Y1 - 2014 U6 - https://doi.org/10.1002/macp.201400166 SN - 1022-1352 SN - 1521-3935 VL - 215 IS - 22 SP - 2268 EP - 2273 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Brosnan, Sarah M. A1 - Schlaad, Helmut T1 - Modification of polypeptide materials by Thiol-X chemistry JF - Polymer : the international journal for the science and technology of polymers N2 - Thiol-X chemistry has proven to be a valuable toolbox for modification of peptides, proteins, monomers, and polymers. Recently, this has become especially true for the modification of polypeptides (monomers or polymers), which has resulted in a plethora of novel polymers and materials. With this in mind, this highlight focuses on the recent literature concerning the modification of polypeptides by the use of thiol-X chemistry, in particular to synthetic polypeptides either at the monomer or polymer stage modified by thiol-ene, -Michael addition, and -yne chemistries. (C) 2014 Published by Elsevier Ltd. KW - Polypeptide KW - Thiol-X KW - Click chemistry Y1 - 2014 U6 - https://doi.org/10.1016/j.polymer.2014.08.067 SN - 0032-3861 SN - 1873-2291 VL - 55 IS - 22 SP - 5511 EP - 5516 PB - Elsevier CY - Oxford ER - TY - JOUR A1 - Chandran, Sivasurender A1 - Dold, Stefanie A1 - Buvignier, Amaury A1 - Krannig, Kai-Steffen A1 - Schlaad, Helmut A1 - Reiter, Günter A1 - Reiter, Renate T1 - Tuning Morphologies of Langmuir Polymer Films Through Controlled Relaxations of Non-Equilibrium States JF - Langmuir N2 - Langmuir polymers films (LPFs) frequently form non-equilibrium states which are manifested in a decay of the surface pressure with time when the system is allowed to relax. Monitoring and manipulating the temporal evolution of these relaxations experimentally helps to shed light on the associated molecular reorganization processes. We present a systematic study based on different compression protocols and show how these reorganization processes impact the morphology of LPFs of poly(gamma-benzyl-L-glutamate) (PBLG); visualized by means of atomic force microscopy. Upon continuous compression, a fibrillar morphology was formed with a surface decorated by squeezed-out islands. By contrast, stepwise compression promoted the formation of a fibrillar network with a bimodal distribution of fibril diameters, caused by merging of fibrils. Finally, isobaric compression induced in-plane compaction of the monolayer. We correlate these morphological observations with the kinetics of the corresponding relaxations, described best by a sum of two exponential functions with different time scales representing two molecular processes. We discuss the observed kinetics and the resulting morphologies in the context of nucleation and growth, characteristic for first-order phase transitions. Our results demonstrate that the preparation conditions of LPFs have tremendous impact on ordering of the molecules and hence various macroscopic properties of such films. Y1 - 2015 U6 - https://doi.org/10.1021/acs.langmuir.5b01212 SN - 0743-7463 VL - 31 IS - 23 SP - 6426 EP - 6435 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - Knecht, Volker A1 - Reiter, Guenter A1 - Schlaad, Helmut A1 - Reiter, Renate T1 - Structure Formation in Langmuir Peptide Films As Revealed from Coarse-Grained Molecular Dynamics Simulations JF - Langmuir N2 - Molecular dynamics simulations in conjunction with the Martini coarse-grained model have been used to investigate the (nonequilibrium) behavior of helical 22-residue poly(gamma-benzyl-L-glutamate) (PBLG) peptides at the water/vapor interface. Preformed PBLG mono- or bilayers homogeneously covering the water surface laterally collapse in tens of nanoseconds, exposing significant proportions of empty water surface. This behavior was also observed in recent AFM experiments at similar areas per monomer, where a complete coverage had been assumed in earlier work. In the simulations, depending on the area per monomer, either elongated clusters or fibrils form, whose heights (together with the portion of empty water surface) increase over time. Peptides tend to align with respect to the fiber axis or with the major principal axis of the cluster, respectively. The aspect ratio of the cluster observed is 1.7 and, hence, comparable to though somewhat smaller than the aspect ratio of the peptides in alpha-helical conformation, which is 2.2. The heights of the fibrils is 3 nm after 20 ns and increases to 4.5 nm if the relaxation time is increased by 2 orders of magnitude, in agreement with the experiment. Aggregates with heights of about 3 or 4.5 nm are found to correspond to local bi- or trilayer structures, respectively. Y1 - 2017 U6 - https://doi.org/10.1021/acs.langmuir.7b01455 SN - 0743-7463 VL - 33 SP - 6492 EP - 6502 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - Debsharma, Tapas A1 - Behrendt, Felix Nicolas A1 - Laschewsky, Andre A1 - Schlaad, Helmut T1 - Ring-opening metathesis polymerization of biomass-derived levoglucosenol JF - Angewandte Chemie : a journal of the Gesellschaft Deutscher Chemiker N2 - The readily available cellulose-derived bicyclic compound levoglucosenol was polymerized through ring-opening metathesis polymerization (ROMP) to yield polylevoglucosenol as a novel type of biomass-derived thermoplastic polyacetal, which, unlike polysaccharides, contains cyclic as well as linear segments in its main chain. High-molar-mass polyacetals with apparent weight-average molar masses of up to 100kgmol(-1) and dispersities of approximately 2 were produced despite the non-living/controlled character of the polymerization due to irreversible deactivation or termination of the catalyst/active chain ends. The resulting highly functionalized polyacetals are glassy in bulk with a glass transition temperature of around 100 degrees C. In analogy to polysaccharides, polylevoglucosenol degrades slowly in an acidic environment. KW - degradable polymers KW - metathesis KW - ring-opening polymerization KW - sustainable chemistry KW - thermoplastics Y1 - 2019 U6 - https://doi.org/10.1002/anie.201814501 SN - 1433-7851 SN - 1521-3773 VL - 58 IS - 20 SP - 6718 EP - 6721 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Kaya, Kerem A1 - Debsharma, Tapas A1 - Schlaad, Helmut A1 - Yagci, Yusuf T1 - Cellulose-based polyacetals by direct and sensitized photocationic ring-opening polymerization of levoglucosenyl methyl ether JF - Polymer Chemistry N2 - This study aims to explore the photoinitiated cationic ring-opening polymerization of levoglucosenyl methyl ether (LGME), a chemical obtained from the most abundant biomass - cellulose. Direct and sensitized photopolymerizations of LGME using photoinitiators acting at the near UV or visible range in conjunction with diphenyliodonium hexafluoroantimonate (DPI) yielded unsaturated polyacetals with varying molar masses and distributions. Y1 - 2020 U6 - https://doi.org/10.1039/d0py01307b SN - 1759-9954 SN - 1759-9962 VL - 11 IS - 43 SP - 6884 EP - 6889 PB - Royal Society of Chemistry CY - Cambridge ER - TY - JOUR A1 - Shkilnyy, Andriy A1 - Brandt, Jessica A1 - Mantion, Alexandre A1 - Paris, Oskar A1 - Schlaad, Helmut A1 - Taubert, Andreas T1 - Calcium phosphate with a channel-like morphology by polymer templating N2 - Calcium phosphate mineralization from aqueous solution in the presence of organic growth modifiers has been intensely studied in the recent past. This is mostly due to potential applications of the resulting composites in the biomaterials field. Polymers in particular are efficient growth modifiers. As a result, there has been a large amount of work on polymeric growth modifiers. Interestingly, however, relatively little work has been done on polycationic additives. The current paper shows that poly(ethylene oxide)b-poly(L-lysine) block copolymers lead to an interesting morphology of calcium phosphate precipitated at room temperature and subjected to a mild heat treatment at 85 degrees C. Electron microscopy, synchrotron X-ray diffraction, and porosity analysis show that a (somewhat) porous material with channel-like features forms. Closer inspection using transmission electron microscopy shows that the channels are probably not real channels. Much rather the morphology is the result of the aggregation of ca. 100-nm-sized rodlike primary particles, which changes upon drying to exhibit the observed channel-like features. Comparison experiments conducted in the absence of polymer and with poly(ethylene oxide)-b-poly(L-glutamate) show that these features only form in the presence of the polycationic poly(L-lysine) block, suggesting a distinct interaction of the polycation with either the crystal or the phosphate ions prior to mineralization. Y1 - 2009 UR - http://pubs.acs.org/journal/cmatex U6 - https://doi.org/10.1021/Cm803244z SN - 0897-4756 ER - TY - JOUR A1 - Casse, Olivier A1 - Shkilnyy, Andriy A1 - Linders, Jürgen A1 - Mayer, Christian A1 - Häussinger, Daniel A1 - Völkel, Antje A1 - Thünemann, Andreas F. A1 - Dimova, Rumiana A1 - Cölfen, Helmut A1 - Meier, Wolfgang P. A1 - Schlaad, Helmut A1 - Taubert, Andreas T1 - Solution behavior of double-hydrophilic block copolymers in dilute aqueous solution JF - Macromolecules : a publication of the American Chemical Society N2 - The self-assembly of double-hydrophilic poly(ethylene oxide)-poly(2-methyl-2-oxazoline) diblock copolymers in water has been studied. Isothermal titration calorimetry, small-angle X-ray scattering, and analytical ultracentrifugation suggest that only single polymer chains are present in solution. In contrast, light scattering and transmission electron microscopy detect aggregates with radii of ca. 100 nm. Pulsed field gradient NMR spectroscopy confirms the presence of aggregates, although only 2% of the polymer chains undergo aggregation. Water uptake experiments indicate differences in the hydrophilicity of the two blocks, which is believed to be the origin of the unexpected aggregation behavior (in accordance with an earlier study by Ke et al. [Macromolecules 2009, 42, 5339-5344]). The data therefore suggest that even in double-hydrophilic block copolymers, differences in hydrophilicity are sufficient to drive polymer aggregation, a phenomenon that has largely been overlooked or ignored so far. Y1 - 2012 U6 - https://doi.org/10.1021/ma300621g SN - 0024-9297 VL - 45 IS - 11 SP - 4772 EP - 4777 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - Yuan, Jiayin A1 - ten Brummelhuis, Niels A1 - Junginger, Mathias A1 - Xie, Zailai A1 - Lu, Yan A1 - Taubert, Andreas A1 - Schlaad, Helmut T1 - Diversified applications of chemically modified 1,2-Polybutadiene JF - Macromolecular rapid communications N2 - Commercially available 1,2-PB was transformed into a well-defined reactive intermediate by quantitative bromination. The brominated polymer was used as a polyfunctional macroinitiator for the cationic ring-opening polymerization of 2-ethyl-2-oxazoline to yield a water-soluble brush polymer. Nucleophilic substitution of bromide by 1-methyl imidazole resulted in the formation of polyelectrolyte copolymers consisting of mixed units of imidazolium, bromo, and double bond. These copolymers, which were soluble in water without forming aggregates, were used as stabilizers in the heterophase polymerization of styrene and were also studied for their ionic conducting properties. KW - emulsion polymerization KW - polybutadiene KW - polyelectrolytes KW - polymer modification KW - ring-opening polymerization Y1 - 2011 U6 - https://doi.org/10.1002/marc.201100254 SN - 1022-1336 VL - 32 IS - 15 SP - 1157 EP - 1162 PB - Wiley-Blackwell CY - Malden ER - TY - JOUR A1 - Goebel, Ronald A1 - Hesemann, Peter A1 - Friedrich, Alwin A1 - Rothe, Regina A1 - Schlaad, Helmut A1 - Taubert, Andreas T1 - Modular thiol-ene chemistry approach towards mesoporous silica monoliths with organically modified pore walls JF - Chemistry - a European journal N2 - The surface modification of mesoporous silica monoliths through thiol-ene chemistry is reported. First, mesoporous silica monoliths with vinyl, allyl, and thiol groups were synthesized through a sol-gel hydrolysis-poly-condensation reaction from tetramethyl orthosilicate (TMOS) and vinyltriethoxysilane, allyltriethoxysilane, and (3-mercaptopropyl) trimethoxysilane, respectively. By variation of the molar ratio of the comonomers TMOS and functional silane, mesoporous silica objects containing different amounts of vinyl, allyl, and thiol groups were obtained. These intermediates can subsequently be derivatized through radical photoaddition reactions either with a thiol or an olefin, depending on the initial pore wall functionality, to yield silica monoliths with different pore-wall chemistries. Nitrogen sorption, small-angle X-ray scattering, solid-state NMR spectroscopy, elemental analysis, thermogravimetric analysis, and redox titration demonstrate that the synthetic pathway influences the morphology and pore characteristics of the resulting monoliths and also plays a significant role in the efficiency of functionalization. Moreover, the different reactivity of the vinyl and allyl groups on the pore wall affects the addition reaction, and hence, the degree of the pore-wall functionalization. This report demonstrates that thiol-ene photoaddition reactions are a versatile platform for the generation of a large variety of organically modified silica monoliths with different pore surfaces. KW - mesoporous materials KW - photochemistry KW - sol-gel processes KW - surface chemistry Y1 - 2014 U6 - https://doi.org/10.1002/chem.201403982 SN - 0947-6539 SN - 1521-3765 VL - 20 IS - 52 SP - 17579 EP - 17589 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Löbbicke, Ruben A1 - Chanana, Munish A1 - Schlaad, Helmut A1 - Pilz-Allen, Christine A1 - Günter, Christina A1 - Möhwald, Helmuth A1 - Taubert, Andreas T1 - Polymer Brush Controlled Bioinspired Calcium Phosphate Mineralization and Bone Cell Growth JF - Biomacromolecules : an interdisciplinary journal focused at the interface of polymer science and the biological sciences N2 - Polymer brushes on thiol-modified gold surfaces were synthesized by using terminal thiol groups for the surface initiated free radical polymerization of methacrylic acid and dimethylaminotheyl methacrylate, respectively. Atomic force microscopy shows that the resulting poly(methacrylic acid (PMAA) and poly(dimethylaminothyl methacrylate) (PDM- AEMA) brushes are homogeneous. Contact angle measurements show that the brushes are pH responsive and can reversibly be protonated and deprotonated. Mineralization of the brushes with calcium phosphate at different pH yields homogeneously mineralized surfaces, and preosteoblastic cells proliferate-on be number of living cells on the mineralized hybrid surface is ca. 3 times (P corresponding nonmineralized brushes. Y1 - 2011 U6 - https://doi.org/10.1021/bm200991b SN - 1525-7797 VL - 12 IS - 10 SP - 3753 EP - 3760 PB - American Chemical Society CY - Washington ER - TY - GEN A1 - Al-Naji, Majd A1 - Schlaad, Helmut A1 - Antonietti, Markus T1 - New (and old) monomers from biorefineries to make polymer chemistry more sustainable T2 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe N2 - This opinion article describes recent approaches to use the "biorefinery" concept to lower the carbon footprint of typical mass polymers, by replacing parts of the fossil monomers with similar or even the same monomer made from regrowing dendritic biomass. Herein, the new and green catalytic synthetic routes are for lactic acid (LA), isosorbide (IS), 2,5-furandicarboxylic acid (FDCA), and p-xylene (pXL). Furthermore, the synthesis of two unconventional lignocellulosic biomass derivable monomers, i.e., alpha-methylene-gamma-valerolactone (MeGVL) and levoglucosenol (LG), are presented. All those have the potential to enter in a cost-effective way, also the mass market and thereby recover lost areas for polymer materials. The differences of catalytic unit operations of the biorefinery are also discussed and the challenges that must be addressed along the synthesis path of each monomers. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 1385 KW - biodegradable polymers KW - biorefineries KW - carbohydrate‐ based KW - monomers KW - green polymers KW - lignocellulosic biomass Y1 - 2020 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-570614 SN - 1866-8372 IS - 3 ER -