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91.
Biodegradable ABA triblock copolymers with poly(ethylene oxide) and poly(glycolic acid‐valine) blocks were synthesized via ring‐opening polymerization of cyclo(glycolic acid‐valine) using Ca‐alcoholates of hydroxytelechelic PEO as the initiator. The L‐valine residue racemized during copolymerization of cyclo(glycolic acid‐valine). The crystallization of the block copolymers decreases with decreasing PEO content in the triblock copolymers and with increasing length of the poly(glycolic acid‐valine) block. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 2916–2919, 2002 相似文献
92.
Marco Sangermano Anna Di Gianni Roberta Bongiovanni Aldo Priola Brigitte Voit Doris Pospiech Dietmar Appelhans 《大分子材料与工程》2005,290(7):721-725
Summary: A fluorine containing hyperbranched polymer was synthesized by modifying an aromatic‐aliphatic hyperbranched polyester with a semifluorinated alcohol via a Mitsunobu reaction and was subsequently used as an additive in cationic photopolymerization of an epoxy resin. The remaining OH groups of the fluorinated hyperbranched polymer interact with the polymeric carbocation through a chain‐transfer mechanism inducing an increase in the final epoxy conversion. The fluorinated HBP induces modification of bulk and surface properties, with an increase in Tg and surface hydrophobicity already reached at very low concentration. The HBFP additive can, therefore, protect the coatings from aggressive solvents, increases hardness, and allows the preparation of a low energy surface coating.
93.
Dorota?Jermakowicz-Bartkowiak Piotr?CyganowskiEmail author Jaros?aw?Kawa?ko 《Polymer Bulletin》2017,74(1):229-244
In the present studies a series of anion-exchange resins was synthesized in a microwave field. The 1,6-diaminohexane functionalized resins were obtained in presence of selected organic solvents, N,N-dimethyl formamide, dimethyl sulfoxide and 1-methyl-2-pyrrolidone. The resins were employed in batch and dynamic processes of Au(III), Pt(IV) and Pd(II) sorption from tricomponent systems in 0.1 M HCl. The experiment was designed in a way that allowed to determine the use of a specific solvent in the microwave field and how it impacts on properties of the anion exchangers. An influence of a reaction environment was discussed taking into account i.e., dielectric characteristics of the specific solvent, efficiency of the syntheses processes as well as the maximum sorption capacity of the resins. Ultimately the application of a specific reaction environment was set together with sorption of noble metals ability and evaluated using infrared spectroscopy. The proceeded analyzes allowed to determine which organic solvent from the selected ones is the most suitable for microwave-assisted synthesis of the anion-exchange resins. 相似文献
94.
Hemmrich K Salber J Meersch M Wiesemann U Gries T Pallua N Klee D 《Journal of materials science. Materials in medicine》2008,19(1):257-267
Biodegradable polyesters are established biomaterials in medicine due to their chemical characteristics and options for material
processing. A main problem, however, is the release of acid degradation products during biodegradation with severe local pH-drops
and inflammatory reactions. Polyesteramides, in contrast, show a less prominent pH-drop during degradation. In this study,
we developed a simple, reproducible synthesis of the poly(ester amide) (PEA) type C starting from ε-caprolactame, 1,4-butanediol,
and adipic acid in a one-batch two-step reaction and conducted the manufacturing of PEA-derived 3D textile scaffolds applicable
for tissue engineering purposes. The thermal and mechanical properties of PEA-type C were analysed and the structural conformity
of different batches was confirmed by NMR spectroscopy and size exclusion chromatography. The polymer was formed into nonwovens
by textile manufacturing. Cytotoxicity tests and X-ray photoelectron spectroscopy (XPS) were used to analyze the effect of
scaffold extraction before cell seeding. The manufactured carriers were seeded with human preadipocytes and examined for cellular
proliferation and differentiation. The production of PEA type C successfully occurred via simultaneous ring-opening polymerization
of ε-caprolactame and polycondensation with 1,4-butanediol and adipic acid at 250 °C under high-vacuum. Soxhlet extraction
allowed optimal cleaning of nonwoven scaffolds. Extracted PEA-derived matrices were capable of allowing good adherence, proliferation,
and differentiation of preadipocytes. These results are encouraging and guidance towards an optimally prepared nonwoven carrier
applicable for clinical use.
K. Hemmrich and J. Salber have contributed equally. 相似文献
95.
The preparation of porous hierarchical architectures that have structural features spanning from the nanometer to micrometer and even larger dimensions and that exhibit certain functionalities is one of the new challenging frontiers in materials chemistry. The sol-gel process is one of the most promising synthesis routes toward such materials because it not only offers the possibility to incorporate organic functions into the porous host but also offers the possibility to deliberately tailor the pore structure. In this Account, the opportunities given by the application of novel diol-modified silanes are discussed for the synthesis of hierarchically organized inorganic and also inorganic-organic porous monoliths. 相似文献
96.
Kloss FR Najam-Ul-Haq M Rainer M Gassner R Lepperdinger G Huck CW Bonn G Klauser F Liu X Memmel N Bertel E Garrido JA Steinmüller-Nethl D 《Journal of nanoscience and nanotechnology》2007,7(12):4581-4587
Nanocrystalline diamond (NCD) has recently been successfully utilized in a variety of life science applications. NCD films are favorable and salubrious substrates for cells during cultivation. Therefore NCD has also been employed in tissue engineering strategies. NCD as reported in this contribution was grown by means of a modified hot-filament chemical vapor deposition technique, which results in less than 3% sp2-hybridization and yields grain sizes of 5-20 nm. After production the NCD surface was rather hydrophobic, however it could be efficiently refined to exhibit more hydrophilic properties. Changing of the surface structure was found to be an efficient means to influence growth and differentiation capacity of a variety of cells. The particular needs for any given cell type has to be proven empirically. Yet flexible features of NCD appear to be superior to plastic surfaces which can be hardly changed in quality. Besides its molecular properties, crystal structural peculiarities of NCD appear to influence cell growth as well. In our attempt to facilitate, highly specialized applications in biomedicine, we recently discovered that growth factors can be tightly bound to NCD by mere physisorption. Hence, combination of surface functionalization together with further options to coat NCD with any kind of three-dimensional structure opens up new avenues for many more applications. In fact, high through-put protein profiling of early disease stages may become possible from serum samples, because proteins bound to NCD can now be efficiently analyzed by MALDI/TOF-MS. Given these results, it is to be presumed that the physical properties and effective electrochemical characteristics of NCD will allow tailoring devices suitable for many more diagnostic as well as therapeutic applications. 相似文献
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100.
Liane Hußler Doris Pospiech Kathrin Eckstein Andreas Janke Roland Vogel 《应用聚合物科学杂志》1997,66(12):2293-2309
The use of multiblock copolymers for the compatibilization of immiscible polymer blends is controversially discussed in the literature. Investigations have been carried out to estimate the effect of multiblock copolymers containing segments of a liquid crystalline polyester (LCP) and polysulfone (PSU) segments in blends of the based homopolymers. One goal was to determine whether multiblock copolymers provide an opportunity for compatibilizing PSU/LCP blends. By using PSU/LCP multiblock copolymers with different molecular weights of the blocks in the appropriate binary, solution-casted blends, it was shown that the interpenetration of the polysulfone phase of the block copolymer and the PSU matrix leads to an improved miscibility of the blend. This effect is retained in ternary blends of PSU, LCP, and the multiblock copolymer, assuming a certain critical molecular weight of the multiblock copolymer segments. In addition, some mechanical characteristics of PSU/LCP melt blends such as the E-modulus and fracture strength are improved by adding long-segmented multiblock copolymers. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 66: 2293–2309, 1997 相似文献