Polychloroprene, poly isoprene

The results of stereochemical interest which came out of this work may be indicated (Bunn, 1942 a-c). It paved the way to a solution of the crystal structure of rubber itself (the cis isomer of poly-isoprene) and of the synthetic rubber-like substance polychloroprene... 

It has been shown that the dihalocarbenes (CX2) react with macro-molecular polyenes to give polydihalocyclopropane type products (17, 18). The transformations effected may be either partial or total on poly-isoprenes and polybutadienes. The reactivity of the polychloroprenes is slighter, and they undergo marked conversion only when they react with CClo. A study was made of the structures obtained and in particular their reduction to polycyclopropane hydrocarbons. 

Addition or chain growth polymers are formed by the direct addition of monomer molecules held together by a covalent bond without loss of any by-product during the polymerisation process. Thus the molecular mass of a monomer molecule and a repeating unit is the same. Examples of this class of polymers are vinyl polymers such as polystyrene, polybutadiene and poly (vinyl chloride), and diene polymers such as polybutadiene, and poly-isoprene, polychloroprene. 

Diene polymers refer to polymers synthesized from monomers that contain two carbon-carbon double bonds (i.e., diene monomers). Butadiene and isoprene are typical diene monomers (see Scheme 19.1). Butadiene monomers can link to each other in three ways to produce ds-1,4-polybutadiene, trans-l,4-polybutadi-ene and 1,2-polybutadiene, while isoprene monomers can link to each other in four ways. These dienes are the fundamental monomers which are used to synthesize most synthetic rubbers. Typical diene polymers include polyisoprene, polybutadiene and polychloroprene. Diene-based polymers usually refer to diene polymers as well as to those copolymers of which at least one monomer is a diene. They include various copolymers of diene monomers with other monomers, such as poly(butadiene-styrene) and nitrile butadiene rubbers. Except for natural polyisoprene, which is derived from the sap of the rubber tree, Hevea brasiliensis, all other diene-based polymers are prepared synthetically by polymerization methods. 

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. 

Some specific recent applications of the chromatography-mass spectrometry technique to various types of polymers include the following PE [130, 131], poly(l-octene), poly(l-decene), poly(l-dodecene) and 1-octene-l-decene-l-dodecene terpolymer [132], chlorinated polyethylene [133], polyolefins [134,135], acrylic acid, methacrylic acid copolymers [136, 137], polyacrylate [138], styrene-butadiene and other rubbers [139-141], nitrile rubber [142], natural rubbers [143,144], chlorinated natural rubber [145,146], polychloroprene [147], PVC [148-150], silicones [151,152], polycarbonates (PC) [153], styrene-isoprene copolymers [154], substituted PS [155], polypropylene carbonate [156], ethylene-vinyl acetate copolymer [157], Nylon 6,6 [158], polyisopropenyl cyclohexane-a-methylstyrene copolymers [195], cresol-novolac epoxy resins [160], polymeric flame retardants [161], poly(4-N-alkylstyrenes) [162], pol)winyl pyrrolidone [31,163], vinyl pyrrolidone-methacryloxysilicone copolymers [164], polybutylcyanoacrylate [165], polysulfide copolymers [1669], poly(diethyl-2-methacryloxy) ethyl phosphate [167, 168], ethane-carbon monoxide copolymers [169], polyetherimide [170], and bisphenol-A [171]. 

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