@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{NaolouLendleinNeffe2019, author = {Naolou, Toufik and Lendlein, Andreas and Neffe, Axel T.}, title = {Amides as non-polymerizable catalytic adjuncts enable the ring-opening polymerization of lactide with ferrous acetate under mild conditions}, series = {Frontiers in Chemistry}, volume = {7}, journal = {Frontiers in Chemistry}, publisher = {Frontiers Research Foundation}, address = {Lausanne}, issn = {2296-2646}, doi = {10.3389/fchem.2019.00346}, pages = {12}, year = {2019}, abstract = {Sn-based catalysts are effective in the ring-opening polymerization (ROP) but are toxic. Fe(OAc)(2) used as an alternative catalyst is suitable for the ROP of lactide only at higher temperatures (>170 degrees C), associated with racemization. In the ROP of ester and amide group containing morpholinediones with Fe(OAc)(2) to polydepsipeptides at 135 degrees C, ester bonds were selectively opened. Here, it was hypothesized that ROP of lactones is possible with Fe(OAc)(2) when amides are present in the reactions mixture as Fe-ligands could increase the solubility and activity of the metal catalytic center. The ROP of lactide in the melt with Fe(OAc)(2) is possible at temperatures as low as 105 degrees C, in the presence of N-ethylacetamide or N-rnethylbenzamide as non-polymerizable catalytic adjuncts (NPCA), with high conversion (up to 99 mol\%) and yield (up to 88 mol\%). Polydispersities of polylactide decreased with decreasing reaction temperature to <= 1.1. NMR as well as polarimetric studies showed that no racemization occurred at reaction temperatures <= 145 degrees C. A kinetic study demonstrated a living chain-growth mechanism. MALDI analysis revealed that no side reactions (e.g., cyclization) occurred, though transesterification took place.}, language = {en} } @article{BehrendtSchlaad2018, author = {Behrendt, Felix Nicolas and Schlaad, Helmut}, title = {Entropy-Driven Ring-Opening Disulfide Metathesis Polymerization for the Synthesis of Functional Poly(disulfide)s}, series = {Macromolecular rapid communications}, volume = {39}, journal = {Macromolecular rapid communications}, number = {6}, publisher = {Wiley-VCH}, address = {Weinheim}, issn = {1022-1336}, doi = {10.1002/marc.201700735}, pages = {4}, year = {2018}, abstract = {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.}, language = {en} } @article{PengBehlZhangetal.2018, author = {Peng, Xingzhou and Behl, Marc and Zhang, Pengfei and Mazurek-Budzynska, Magdalena and Feng, Yakai and Lendlein, Andreas}, title = {Synthesis of Well-Defined Dihydroxy Telechelics by (Co)polymerization of Morpholine-2,5-Diones Catalyzed by Sn(IV) Alkoxide}, series = {Macromolecular bioscience}, volume = {18}, journal = {Macromolecular bioscience}, number = {12}, publisher = {Wiley-VCH}, address = {Weinheim}, issn = {1616-5187}, doi = {10.1002/mabi.201800257}, pages = {11}, year = {2018}, abstract = {Well-defined dihydroxy telechelic oligodepsipeptides (oDPs), which have a high application potential as building blocks for scaffold materials for tissue engineering applications or particulate carrier systems for drug delivery applications are synthesized by ring-opening polymerization (ROP) of morpholine-2,5-diones (MDs) catalyzed by 1,1,6,6-tetra-n-butyl-1,6-distanna-2,5,7,10-tetraoxacyclodecane (Sn(IV) alkoxide). In contrast to ROP catalyzed by Sn(Oct)(2), the usage of Sn(IV) alkoxide leads to oDPs, with less side products and well-defined end groups, which is crucial for potential pharmaceutical applications. A slightly faster reaction of the ROP catalyzed by Sn(IV) alkoxide compared to the ROP initiated by Sn(Oct)(2)/EG is found. Copolymerization of different MDs resulted in amorphous copolymers with T(g)s between 44 and 54 degrees C depending on the molar comonomer ratios in the range from 25\% to 75\%. Based on the well-defined telechelic character of the Sn(IV) alkoxide synthesized oDPs as determined by matrix-assisted laser desorption/ionization time of flight measurements, they resemble interesting building blocks for subsequent postfunctionalization or multifunctional materials based on multiblock copolymer systems whereas the amorphous oDP-based copolymers are interesting building blocks for matrices of drug delivery systems.}, language = {en} } @article{DoritiBrosnanWeidneretal.2016, author = {Doriti, Afroditi and Brosnan, Sarah M. and Weidner, Steffen M. and Schlaad, Helmut}, title = {Synthesis of polysarcosine from air and moisture stable N-phenoxycarbonyl-N-methylglycine assisted by tertiary amine base}, series = {Polymer Chemistry}, volume = {7}, journal = {Polymer Chemistry}, publisher = {RSC Publ.}, address = {Cambridge}, issn = {1759-9954}, doi = {10.1039/C6PY00221H}, pages = {3067 -- 3070}, year = {2016}, abstract = {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.}, language = {en} } @article{SeckerBrosnanLuxenhoferetal.2015, author = {Secker, Christian and Brosnan, Sarah M. and Luxenhofer, Robert and Schlaad, Helmut}, title = {Poly(alpha-Peptoid)s Revisited: Synthesis, Properties, and Use as Biomaterial}, series = {Macromolecular bioscience}, volume = {15}, journal = {Macromolecular bioscience}, number = {7}, publisher = {Wiley-VCH}, address = {Weinheim}, issn = {1616-5187}, doi = {10.1002/mabi.201500023}, pages = {881 -- 891}, year = {2015}, abstract = {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).}, 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} }