Poly block copolymer elongation

Various linear block copolymers of the AB, ABA and ABC type with enzymatically polymerized amylose blocks were reported. Ziegast and Pfannemuller converted the hydroxyl end groups of poly(ethylene oxide) into amino groups via tosylation and further reaction with 2-aminoalkylthiolate. To the resulting mono- and di-amino functionalized poly(ethylene oxide) maltooligosaccharide lactones were attached and subsequently elongated to amylose via enzymatic polymerization. Pfannemuller et al. performed a very detailed study on the solution properties of the synthesized A-B-A triblock... 

Orientations in elongated mbbers are sometimes regular to the extent that there is local crystallization of individual chain segments (e.g., in natural rubber). X-ray diffraction patterns of such samples are very similar to those obtained from stretched fibers. The following synthetic polymers are of technical relevance as mbbers poly(acrylic ester)s, polybutadienes, polyisoprenes, polychloroprenes, butadiene/styrene copolymers, styrene/butadiene/styrene tri-block-copolymers (also hydrogenated), butadiene/acrylonitrile copolymers (also hydrogenated), ethylene/propylene co- and terpolymers (with non-conjugated dienes (e.g., ethylidene norbomene)), ethylene/vinyl acetate copolymers, ethyl-ene/methacrylic acid copolymers (ionomers), polyisobutylene (and copolymers with isoprene), chlorinated polyethylenes, chlorosulfonated polyethylenes, polyurethanes, silicones, poly(fluoro alkylene)s, poly(alkylene sulfide)s. 

ABA coil-rod-coil copolymers of poly(p-phenylene ter-ephthalamide) (PPTA) or poly(p-benzamide) (PBA) rods and nylon 6 or nylon 6,6 coils were prepared and used to reinforce nylon 6 and nylon 6,6 homopolymers. Materials with 5% total rod in the block copolymer/homo-polymer blend showed improved modulus and tensile strength over the homopolymer and much better elongation to break than similar composition blends of rod and coil homopolymers. The dispersed nature of the rod blocks in the block copolymer prevents the initiation of cracks at the macrophase-separated rod-coil phase interface that would normally occur in a rod/coil homopolymer blend. 

Lin and co-workers [47] reinforced PU elastomers with an entirely rigid aromatic polyamide, poly(w-phenyleneisophthalamide). The block copolymers formed exhibited glass transition temperatures (Tg) under 0 °C. Such block copolymers have improved reinforcing affect as shown by both their tensile strength and elongation when compared with the virgin PU. 

In a rod-coil block copolymer with poly(propylene oxide) as the coil segment and a slightly elongated rod segment (4Cbiphenylcarboxy-4 -biphenyl-4-n-propyloxybenzoate) the already mentioned honeycomb morphology (see Figure 49) was found as well [168]. 

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