PREPARATION OF STEREOREGULAR BLOCK COPOLYMER COMPRISING ISOTACTIC PMMA AND POLYISOBUTYLENE BLOCKS AND ITS CHARACTERIZATION

A triblock copolymer of isotactic(it)-poly(methyl methacrylate) (PMMA) and polyisobutylene (PIB), it-PMMA-block-PIB-block-it-PMMA, was prepared by anionic polymerization of triphenylmethyl methacrylate initiated with alpha, omega-dilithiated PIB diisobutyrate in tetrahydrofuran at -78-degrees-C, and subsequent hydrolysis and methylation with diazomethane. Molecular weight distribution of the triblock copolymer was narrow, and the stereoregularity of the PMMA block was highly isotactic. Proton spin-lattice relaxation times of the block copolymer in acetone-d6, which is non-solvent for PIB but dissolves the block copolymer, indicate the aggregation of the copolymer through PIB block. Stereocomplex formation between the it-block copolymer and syndiotactic(st)-PMMA-block-PIB-block-st-PMMA was also studied.