@article{GressHeiligSmarslyetal.2009, author = {Gress, Anja and Heilig, Anne and Smarsly, Bernd M. and Heydenreich, Matthias and Schlaad, Helmut}, title = {Hydrogen-bonded polymer nanotubes in water}, issn = {0024-9297}, doi = {10.1021/Ma900227t}, year = {2009}, abstract = {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.}, language = {en} } @article{SchlaadYouSigeletal.2009, author = {Schlaad, Helmut and You, Liangchen and Sigel, Reinhard and Smarsly, Bernd and Heydenreich, Matthias and Mantion, Alexandre and Masic, Admir}, title = {Glycopolymer vesicles with an asymmetric membrane}, issn = {1359-7345}, doi = {10.1039/B820887e}, year = {2009}, abstract = {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).}, language = {en} } @article{TritschlerZlotnikovKeckeisetal.2014, author = {Tritschler, Ulrich and Zlotnikov, Igor and Keckeis, Philipp and Schlaad, Helmut and C{\"o}lfen, Helmut}, title = {Optical properties of self-organized gold nanorod-polymer hybrid films}, series = {Langmuir}, volume = {30}, journal = {Langmuir}, number = {46}, publisher = {American Chemical Society}, address = {Washington}, issn = {0743-7463}, doi = {10.1021/la503507u}, pages = {13781 -- 13790}, year = {2014}, abstract = {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.}, language = {en} } @article{FuehrerSchlaad2014, author = {Fuehrer, Felix N. and Schlaad, Helmut}, title = {ADMET polymerization of amino-acid-based diene}, series = {Macromolecular chemistry and physics}, volume = {215}, journal = {Macromolecular chemistry and physics}, number = {22}, publisher = {Wiley-VCH}, address = {Weinheim}, issn = {1022-1352}, doi = {10.1002/macp.201400166}, pages = {2268 -- 2273}, year = {2014}, abstract = {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.}, language = {en} } @article{BrosnanSchlaad2014, author = {Brosnan, Sarah M. and Schlaad, Helmut}, title = {Modification of polypeptide materials by Thiol-X chemistry}, series = {Polymer : the international journal for the science and technology of polymers}, volume = {55}, journal = {Polymer : the international journal for the science and technology of polymers}, number = {22}, publisher = {Elsevier}, address = {Oxford}, issn = {0032-3861}, doi = {10.1016/j.polymer.2014.08.067}, pages = {5511 -- 5516}, year = {2014}, abstract = {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.}, language = {en} } @article{DebsharmaBehrendtLaschewskyetal.2019, author = {Debsharma, Tapas and Behrendt, Felix Nicolas and Laschewsky, Andre and Schlaad, Helmut}, title = {Ring-opening metathesis polymerization of biomass-derived levoglucosenol}, series = {Angewandte Chemie : a journal of the Gesellschaft Deutscher Chemiker}, volume = {58}, journal = {Angewandte Chemie : a journal of the Gesellschaft Deutscher Chemiker}, number = {20}, publisher = {Wiley-VCH}, address = {Weinheim}, issn = {1433-7851}, doi = {10.1002/anie.201814501}, pages = {6718 -- 6721}, year = {2019}, abstract = {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.}, language = {en} } @article{KayaDebsharmaSchlaadetal.2020, author = {Kaya, Kerem and Debsharma, Tapas and Schlaad, Helmut and Yagci, Yusuf}, title = {Cellulose-based polyacetals by direct and sensitized photocationic ring-opening polymerization of levoglucosenyl methyl ether}, series = {Polymer Chemistry}, volume = {11}, journal = {Polymer Chemistry}, number = {43}, publisher = {Royal Society of Chemistry}, address = {Cambridge}, issn = {1759-9954}, doi = {10.1039/d0py01307b}, pages = {6884 -- 6889}, year = {2020}, abstract = {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.}, language = {en} } @article{ShkilnyyBrandtMantionetal.2009, author = {Shkilnyy, Andriy and Brandt, Jessica and Mantion, Alexandre and Paris, Oskar and Schlaad, Helmut and Taubert, Andreas}, title = {Calcium phosphate with a channel-like morphology by polymer templating}, issn = {0897-4756}, doi = {10.1021/Cm803244z}, year = {2009}, abstract = {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.}, language = {en} } @article{CasseShkilnyyLindersetal.2012, author = {Casse, Olivier and Shkilnyy, Andriy and Linders, J{\"u}rgen and Mayer, Christian and H{\"a}ussinger, Daniel and V{\"o}lkel, Antje and Th{\"u}nemann, Andreas F. and Dimova, Rumiana and C{\"o}lfen, Helmut and Meier, Wolfgang P. and Schlaad, Helmut and Taubert, Andreas}, title = {Solution behavior of double-hydrophilic block copolymers in dilute aqueous solution}, series = {Macromolecules : a publication of the American Chemical Society}, volume = {45}, journal = {Macromolecules : a publication of the American Chemical Society}, number = {11}, publisher = {American Chemical Society}, address = {Washington}, issn = {0024-9297}, doi = {10.1021/ma300621g}, pages = {4772 -- 4777}, year = {2012}, abstract = {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.}, language = {en} } @article{YuantenBrummelhuisJungingeretal.2011, author = {Yuan, Jiayin and ten Brummelhuis, Niels and Junginger, Mathias and Xie, Zailai and Lu, Yan and Taubert, Andreas and Schlaad, Helmut}, title = {Diversified applications of chemically modified 1,2-Polybutadiene}, series = {Macromolecular rapid communications}, volume = {32}, journal = {Macromolecular rapid communications}, number = {15}, publisher = {Wiley-Blackwell}, address = {Malden}, issn = {1022-1336}, doi = {10.1002/marc.201100254}, pages = {1157 -- 1162}, year = {2011}, abstract = {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.}, language = {en} } @article{GoebelHesemannFriedrichetal.2014, author = {Goebel, Ronald and Hesemann, Peter and Friedrich, Alwin and Rothe, Regina and Schlaad, Helmut and Taubert, Andreas}, title = {Modular thiol-ene chemistry approach towards mesoporous silica monoliths with organically modified pore walls}, series = {Chemistry - a European journal}, volume = {20}, journal = {Chemistry - a European journal}, number = {52}, publisher = {Wiley-VCH}, address = {Weinheim}, issn = {0947-6539}, doi = {10.1002/chem.201403982}, pages = {17579 -- 17589}, year = {2014}, abstract = {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.}, language = {en} } @article{LoebbickeChananaSchlaadetal.2011, author = {L{\"o}bbicke, Ruben and Chanana, Munish and Schlaad, Helmut and Pilz-Allen, Christine and G{\"u}nter, Christina and M{\"o}hwald, Helmuth and Taubert, Andreas}, title = {Polymer Brush Controlled Bioinspired Calcium Phosphate Mineralization and Bone Cell Growth}, series = {Biomacromolecules : an interdisciplinary journal focused at the interface of polymer science and the biological sciences}, volume = {12}, journal = {Biomacromolecules : an interdisciplinary journal focused at the interface of polymer science and the biological sciences}, number = {10}, publisher = {American Chemical Society}, address = {Washington}, issn = {1525-7797}, doi = {10.1021/bm200991b}, pages = {3753 -- 3760}, year = {2011}, abstract = {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.}, language = {en} } @article{ChandranDoldBuvignieretal.2015, author = {Chandran, Sivasurender and Dold, Stefanie and Buvignier, Amaury and Krannig, Kai-Steffen and Schlaad, Helmut and Reiter, G{\"u}nter and Reiter, Renate}, title = {Tuning Morphologies of Langmuir Polymer Films Through Controlled Relaxations of Non-Equilibrium States}, series = {Langmuir}, volume = {31}, journal = {Langmuir}, number = {23}, publisher = {American Chemical Society}, address = {Washington}, issn = {0743-7463}, doi = {10.1021/acs.langmuir.5b01212}, pages = {6426 -- 6435}, year = {2015}, abstract = {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.}, language = {en} } @article{KnechtReiterSchlaadetal.2017, author = {Knecht, Volker and Reiter, Guenter and Schlaad, Helmut and Reiter, Renate}, title = {Structure Formation in Langmuir Peptide Films As Revealed from Coarse-Grained Molecular Dynamics Simulations}, series = {Langmuir}, volume = {33}, journal = {Langmuir}, publisher = {American Chemical Society}, address = {Washington}, issn = {0743-7463}, doi = {10.1021/acs.langmuir.7b01455}, pages = {6492 -- 6502}, year = {2017}, abstract = {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.}, language = {en} } @article{NoackSchanzenbachKoetzetal.2018, author = {Noack, Sebastian and Schanzenbach, Dirk and Koetz, Joachim and Schlaad, Helmut}, title = {Polylactide-based amphiphilic block copolymers}, series = {Macromolecular rapid communications}, volume = {40}, journal = {Macromolecular rapid communications}, number = {1}, publisher = {Wiley-VCH}, address = {Weinheim}, issn = {1022-1336}, doi = {10.1002/marc.201800639}, pages = {6}, year = {2018}, abstract = {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.}, language = {en} } @article{MaticHessSchanzenbachetal.2020, author = {Matic, Aleksandar and Hess, Andreas and Schanzenbach, Dirk and Schlaad, Helmut}, title = {Epoxidized 1,4-polymyrcene}, series = {Polymer chemistry}, volume = {11}, journal = {Polymer chemistry}, number = {7}, publisher = {Royal Society of Chemistry}, address = {Cambridge}, issn = {1759-9954}, doi = {10.1039/c9py01783f}, pages = {1364 -- 1368}, year = {2020}, abstract = {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.}, language = {en} } @article{GlatzelNoackSchanzenbachetal.2020, author = {Glatzel, Julia and Noack, Sebastian and Schanzenbach, Dirk and Schlaad, Helmut}, title = {Anionic polymerization of dienes in 'green' solvents}, series = {Polymer international}, volume = {70}, journal = {Polymer international}, number = {2}, publisher = {Wiley}, address = {Hoboken}, issn = {0959-8103}, doi = {10.1002/pi.6152}, pages = {181 -- 184}, year = {2020}, abstract = {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.}, language = {en} }