Poly isobutylene-co-p-methylstyrene

Brominated diphenyl oxides, 77 461 Brominated epoxies, 70 383 Brominated epoxy ohgomers, 77 470 Brominated epoxy resin, 70 456 Brominated poly(isobutylene-co-p-methylstyrene), 4 438 blends with halobutyl, 4 453 copolymers, 4 446 vulcanization, 4 450 Brominated polystyrene(s), 77 470 474 20 65... 

A Novel Reactive Functionalization of Polyolefin Elastomers Direct Functionalization of Poly(isobutylene-co-p-methylstyrene) by a Friedel-Crafts Acylation Reaction... 

Butyl rubber consists mostly of isobutylene (95-98%) and about 2-5% isoprene units. 1 The isoprene unit is halogenated by either chlorine or bromine to obtain the corresponding halobutyl rubbers. Despite the superior elastomeric properties of halobutyl, the elastomer can easily undergo dehydrohalogenation leading to crosslinfang, and the isoprene unsaturation is subject to ozone cracking. To remedy these problems and to improve the halobutyl properties, a new class of elastomer poly(isobutylene-co-p-methylstyrene) [poly (IB-PMS)] was developed. Unlike butyl rubber, it contains no double bonds and therefore cannot be crosslinked unless otherwise functionalized. The chemical structures of butyl rubber and poly (IB-PMS) copolymers are shown below. 

The benzyl bromide in the brominated copolymer can also be easily converted by nucleophilic substitution reactions to a variety of other functional groups and graft copolymers as desired for specific properties and applications (47). lonomers (48), grafted copolymers (49), radiation-cured rubbers (50), and rubber-toughened nylons (51) are a few examples of the derivatives and fimctions that modification of brominated poly(isobutylene-co-p-methylstyrene) can offer. 

Vulcanization. Vulcanization or curing in isobutylene polymers introduces chemical cross-links via reactions involving either allylic hydrogen or al-lylic halogen in butyl or halobutyl, respectively, or benzylic bromine in brominated poly(isobutylene-co-p-methylstyrene) to form a polymer network. In butyl... 

Blends of halobutyl or brominated poly(isobutylene-co-p-methylstyrene) with high diene rubbers are used in tire sidewalls and tread compoimds (137-139). In sidewalls, ozone resistance, crack cut growth, and appearance are critical to their performance. Properly formulated blends with high diene rubbers that exhibit phase cocontinuity yield excellent sidewalls (140). The property balance for tire tread compounds can be enhanced by the incorporation of a more damping halobutyl or brominated poly(isobutylene-co-p-methylstyrene) rubber phase (141). Improvements in wet-, snow-, and ice-skid resistances and in dry traction without compromises in abrasion resistance and rolling resistance for high performance tires can be accomplished by using bromobutyl or brominated poly(isobutylene-co-p-methylstyrene) up to 30 pbr in tread compoimds (142). 

Another commercially available polymer, poly(isobutylene-co-p-methylstyrene-co-p-bromomethylstyrene), was used as a macroinitiator for the ATRP of St to produce a graft copolymer (160). After 23 h at 100°C, with 1 equivalent of catalyst relative to the number of moles of initiator, monomer conversion was 81% however, increasing the concentration of catalyst fivefold resulted in the same efficiency after only 11 h. No evidence of imreacted macroinitiator was found in the GPC analysis, indicating that nearly all of the chains contained some grafted sites. Results from mechanical analysis showed that when the wt% of St was high (28%), the graft copol5mier exhibited no special properties however, with only 6 wt% pSt, the polymer was elastomeric and could be reversibly stretched to 500% of its initial dimension (160). 

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