Search results for "Copolymer"
showing 10 items of 1003 documents
Oxazoline-containing compatibilizers for polyamide/SAN and polyamide/ABS blends
2002
Polyamide (PA) and acrylonitrile/butadiene/styrene copolymer (ABS) may appear as a mixture in the recycled plastic stream. The incompatibility of these blends results in a blend with poor mechanical properties. The aim of this work is to partially convert the nitrile groups of the acrylonitrile/styrene copolymer (SAN) into oxazoline groups by reaction with aminoethanol (AE). Such modified SAN (SAN-m) can react with the amine or carboxylic acid end groups of PA, and therefore used as compatibilizers for blends of PA with ABS. SAN-m was found to reduce the SAN-domain size in the PA/SAN-blends. The initial acrylonitrile content of SAN-m had a strong influence on the degree of conversion into o…
Understanding the physical and/or chemical interaction in POSS-poly(ethylene-co-acrylic acid) nanocomposites
2012
P(HPMA)-block-P(LA) copolymers in paclitaxel formulations: Polylactide stereochemistry controls micellization, cellular uptake kinetics, intracellula…
2012
In order to explore the influence of polymer microstructure and stereochemistry in biological settings, the synthesis, micellization, cellular fate and the use in paclitaxel formulations of poly(N-(2-hydroxypropyl)-methacrylamide)-block-poly(L-lactide) (P(HPMA)-block-P(LLA)) and poly(N-(2-hydroxypropyl)-methacrylamide)-block-poly(DL-lactide) block copolymers (P(HPMA)-block-P(DLLA)) were studied. To this end, P(HPMA)-block-P(lactide) block copolymers and their fluorescently labeled analogues were synthesized. The polymers exhibited molecular weights M-n around 20,000 g/mol with dispersities (D=M-w/M-n) below 1.3. In addition, the solution conformation of this new type of partially degradable…
Adhesion prophylaxis using a copolymer with rationally designed material properties.
2008
Physical barriers are the only licensed adjuncts for adhesion prophylaxis in the United States and Europe. Here, we investigate D,L-polylactide-epsilon-caprolactonetrimethylenecarbonate (PCT copolymer), which is a rationally designed biomaterial, as an adhesion barrier.PCT copolymer membranes were produced by polymerization of the monomers, dissolution in organic solvents, and subsequently processing them by means of modified phase inversion and freeze drying. In vitro cytotoxicity was assayed by fibroblast culture. In vivo adhesion prophylaxis was studied in a rat model that involved standardized traumatization by electrocautery and suturing. The quantity and quality of the resulting adhes…
ABC and BAC triblock copolymers - morphological engineering by variation of the block sequence
1997
Different morphologies and phase transitions of ternary triblock copolymers with different block sequences (ABC and BAC) are discussed qualitatively. The interplay between interfacial energies and elastic energies of the different blocks leads to various morphologies and enhances or prevents mixing of different blocks, depending on composition and topology.
Orientation and Dynamics of ZnO Nanorod Liquid Crystals in Electric Fields.
2010
ZnO nanorod polymer hybrids (i.e., ZnO nanorods coated with a block copolymer with a short anchor block (dopamine) and a longer solubilizing block of polystyrene (PS)) form liquid crystalline (LC) phases if they are dispersed at high concentration e.g., in a PS oligomer matrix. Due to the high mobility of the low T(g)-matrix the nanorod polymer hybrids show a switching behavior under an applied AC electric field. Hence, the orientation of the nanorod mesogens can be changed from planar (parallel to the substrate) to homeotropic (perpendicular) in full analogy to the switching of low molecular liquid crystals in an electric field. Dielectric measurements show that such a switching is mainly …
Order-Order Phase Transitions Induced by Supercritical Carbon Dioxide in Triblock Copolymer Thin Films
2019
We study the influence of supercritical carbon dioxide (scCO2) on the phase behavior of a cylinder-forming polystyrene-block-polybutadiene-b-polystyrenetriblock copolymer thin film. Solvent annealing with scCO2 can produce patterns with long-range order but these structures become unstable for thin films with small thicknesses. These results are in good agreement with self-consistent mean field calculations, which indicate that a drying transition occurs for thicknesses below the radius of gyration of the molecule.After decompression and solvent extraction, the initially swollen polymer nanostructure suffers a strong reduction in the average domain spacing, which has a deleterious effect on…
Synthesis and luminescence of poly(phenylacetylene)s with pendant iridium complexes and carbazole groups
2010
Poly(phenylacetylene)s containing pendant phosphorescent iridium complexes have been synthesized and their electrochemical, photo- and electroluminescent properties studied. The polymers have been synthesized by rhodium-catalyzed copolymerization of 9-(4-ethynylphenyl)carbazole (CzPA) and phenylacetylenes (C∧N)2Ir(κ2-O,O′-MeC(O)CHC(O)C6H4CCH-4) (C∧N = κ2-N,C1-2-(pyridin-2-yl)phenyl (IrppyPA) or κ2-N,C1-2-(isoquinolin-1-yl)phenyl (IrpiqPA)). In addition, organic poly(phenylacetylene)s with pendant carbazole groups have been synthesized by rhodium-catalyzed copolymerization of CzPA and 1-ethynyl-4-pentylbenzene. Complex (C∧N)2Ir(κ2-O,O′-MeC(O)CHC(O)Ph) (IrpiqPh; C∧N = 2-(isoquinolin-1-yl)phen…
An insight into the interaction between functionalized thermoplastic elastomer and layered double hydroxides through rheological investigations
2018
Abstract Nanocomposites based on maleated poly(styrene-(ethylene-co-butylene)-styrene) copolymer (SEBSgMA) and organo-modified layered double hydroxide (OLDH) have been formulated with the aim to investigate the effects of interfacial interactions between the grafted maleic anhydride groups of the copolymer and the OLDH nanolayers on the rheological properties of nanocomposites. The spectroscopic analysis indicates the establishment of specific polymer/nanofiller interactions, whose extent has been highlighted through morphological and rheological investigations. Specifically, oscillatory melt rheology and shear relaxation tests have been considered in order to deeply investigate the interf…