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 - Sauter, Tilman A1 - Geiger, Brett A1 - Kratz, Karl A1 - Lendlein, Andreas T1 - Encasement of metallic cardiovascular stents with endothelial cell-selective copolyetheresterurethane microfibers JF - Polymers for advanced technologies N2 - Cardiovascular metallic stents established in clinical application are typically coated by a thin polymeric layer on the stent struts to improve hemocompatibility, whereby often a drug is added to the coating to inhibit neointimal hyperplasia. Besides such thin film coatings recently nano/microfiber coated stents are investigated, whereby the fibrous coating was applied circumferential on stents. Here, we explored whether a thin fibrous encasement of metallic stents with preferentially longitudinal aligned fibers and different local fiber densities can be achieved by electrospinning. An elastic degradable copolyetheresterurethane, which is reported to selectively enhance the adhesion of endothelial cells, while simultaneously rejecting smooth muscle cells, was utilized for stent coating. The fibrous stent encasements were microscopically assessed regarding their single fiber diameters, fiber covered area and fiber alignment at three characteristic stent regions before and after stent expansion. Stent coatings with thicknesses in the range from 30 to 50 mu m were achieved via electrospinning with 1,1,1,3,3,3-hexafluoro-2-propanol (HFP)-based polymer solution, while a mixture of HFP and formic acid as solvent resulted in encasements with a thickness below 5 mu m comprising submicron sized single fibers. All polymeric encasements were mechanically stable during expansion, whereby the fibers deposited on the struts remained their position. The observed changes in fiber density and diameter indicated diverse local deformation mechanisms of the microfibers at the different regions between the struts. Based on these results it can be anticipated that the presented fibrous encasement of stents might be a promising alternative to stents with polymeric strut coatings releasing anti-proliferative drugs. Copyright (c) 2015 John Wiley & Sons, Ltd. KW - multifunctional polymers KW - stent coatings KW - electrospinning KW - biomaterials KW - degradable polymers Y1 - 2015 U6 - https://doi.org/10.1002/pat.3583 SN - 1042-7147 SN - 1099-1581 VL - 26 IS - 10 SP - 1209 EP - 1216 PB - Wiley-Blackwell CY - Hoboken ER -