Copolymers of isoprene

Several polymers based on 1,3-dienes are used as elastomers. These include styrene-1,3-butadiene (SBR), styrene-1,3-butadiene terpolymer with an unsaturated carboxylic acid (carboxylated SBR), acrylonitrile-1,3-butadiene (NBR or nitrile rubber) (Secs. 6-8a, 6-8e), isobutylene-isoprene (butyl rubber) (Sec. 5-2i-l), and block copolymers of isoprene or... 

Among copolymers containing isoprene, AB and ABA block copolymers of styrene and isoprene have been the most studied, but interesting results have also been obtained with copolymers of isoprene and vinylpyridine and of isoprene and methyl methacrylate. 

AB copolymers of isoprene and methyl methacrylate have been synthetized by Rossi205. A hexagonal structure formed by cylinders of polyisoprene in a matrix of poly(methyl methacrylate) has been demonstrated by low-angle X-ray diffraction and electron microscopy for copolymers containing about 30% of polyisoprene209. ... 

Isoprene is converted to elastomers such as poly(m-1,4-isoprene), which is tough, elastic, and resistant to weathering and is used mainly for vehicle tires. Recently, block copolymers of isoprene with styrene have been finding use as thermoplastic elastomers and pressure-sensitive adhesives. 

Mesophases prepared by dissolution of the copolymer in a preferential solvent for the poly(vinylpyridine) block (acrylic acid, nitromethane, dfoxane, octanol, methylethyl ketone, ethyl acetate, vinyl acetate, styrene and methyl methaaylate) and dry copolymers obtained by slow evaporation of the solvent from the mesophases have been studied by low-angle X-r diffraction electron microscopy Copolymers of isoprene and vinylpyridine exhibit cylindrical hexagonal or lamellar structures dependii upon their comi siton.The influence of the nature, concentration, and polymerization of the solvent, molecular weight and composition of the copolymer, microstructure of the polyisoprene block, and position of the nitrogen atom in the vinylpyridine block on the values of the geometrical parameters of the periodic structures have been establidied ... 

AB copolymers of isoprene and methyl methacrylate have been synthetized by Rossi A hexagonal structure formed by cylinders of polyisoprene in a matrix of poly(methyl methaaylate) has been demonstrated by low-ai e X-ray diffraction and electron miaoscopy for copolymers containing about 30% of polyisoprene ABA copolymers poly(methyl methacrylate)-polyisoprene-poly(methyl methacrylate) havii polyisoprene with a high vinyl content as central block have been nthetized by Cole et al. Dynamic mechanical properties of films of these ABA copolymers have been studied as a function of the copolymer composition, the temperature and the nature of the solvent (carbon tetrachloride, toluene, ethyl acetate, methylethyl ketone, dioxane) used for film preparation ... 

Fig. 15 Structures of copolymers of isoprene/hexa-1,5-diene (a) and isoprene/octa-1,7-diene (b)...

Several different elastomers, copolymers of butadiene, are produced commercially. The major ones are copolymers of butadiene with styrene and butadiene with acrylonitrile. Some terpolymers, where the third component is an unsaturated carboxylic acid, are also manufactured. Block copolymers of isoprene with styrene and butadiene with styrene are important commercial elastomers. 

Anionic polymerization of lactams offers the best approach to the preparation of polyamide containing block copolymers. Styrene-nylon 6 block copolymers were prepared by adding e-caprolactam to polystyrene macroanions terminated with bisphenol A bis(chlorofor-mate)(31). Yamashita prepared ABA block copolymers of styrene-a-pyrrolidone and styrene- -caprolactam by sequential addition to styrene macroanions( ). Similarly Stehlik and Sebenda prepared N-acrylamide containing block copolymers(33). Block copolymers of isoprene-pivalolactam have also been reported( . In these cases the lactam was added to "living" polyisoprene anions. 

Hashimoto found in the disordered state for a pure block copolymer of isoprene and styrene by analysis of scattering intensity fluctuation ... 

Polyisoprene has also been pyrolysed in an inert atmosphere and here the main products are isoprene and l-methyl-4-isoprenylcyclohexene. The latter compound can disproportionate to l-methyl-4-isopropyIbenzene and methyl-l-iso-propylcyclohexenes and this reaction is catalysed by Ziegler-Natta catalyst residues or by carbon black. The dominant initiation process is j9-chain scission with the formation of two allylic radicals. The kinetics of thermal decomposition have been studied for cis- and rraiw-1,4-polyisoprene and the copolymer of isoprene with 4-isopropyl-methyl styrene and also for isoprene polymers containing 4-CjH4—Z—4-C(H4— and —CjH4—Z—C5H4N=N— units, where Z may be O, CHj, SOj or a single bond. ... 

Draw the structure of an alternating segment of butyl rubber, a copolymer of isoprene (2-methyl-l,3-butadiene) and isobutylene (2-methylpropene) prepared using a cationic initiator. 

Lbbach and coworkers [80] prepared copolymers of isoprene and butadiene in which monomer units had either predominantly 1,4-cis- or 1,4-trans- configurations and investigated their cmr spectra. Assignments were made for the various aliphatic carbon resonances... 

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