Preparing a functionalized thermoplastic elastomer -: Bromination and synthesis of poly(p-methylstyrene-co-styrene)-block-poly(ethylene-co-butene)-block-poly(p-methylstyrene-co-styrene)

A poly(p-methylstyrene-co-styrene)-block-poly(ethylene-co-butene)-block-poly(p-methylstyrene-co-styrene) thermoplastic elastomer was prepared via anionic synthesis of poly(p-methylstyrene-co-styrene)-block-polybutadiene-block-poly(p-methylstyrene-co-styrene) followed by a hydrogenation of the polybutadiene midblock, The sequential method used for the synthesis has resulted in a nearly monodispersed polymer with a polydispersity of 1.03. Bromination of such synthesized copolymer was next, conducted using two different methods. In the presence of a FeCl3 catalyst in CCl4 solvent, bromination occurred through forming a carbocationic complex to undergo an electrophilic substitution reaction on the aromatic rings of the end blocks. Nevertheless, the bromination occurred exclusively on the p-methyl groups of the end blocks when conducted in cyclohexane using photoinitiated free radicals. The microstructure of the brominated molecules were analyzed using H-1-NMR and C-13-NMR, and bromination efficiencies of 48 and 44% have been attained from the two methods, respectively. (C) 1999 John Wiley & Sons, Inc.