REACTIVE POLYMERS INCORPORATING SILYL ENOL ETHER GROUPS, 3 - INCORPORATION OF ALPHA,BETA-BIS(SILOXY)VINYLENE UNITS INTO THE BACKBONE OF VINYL-POLYMERS BY FREE-RADICAL (CO)POLYMERIZATION OF 2,3-BIS(TRIALKYLSILOXY)BUTADIENES

2,3-Bis(trimethylsiloxy)butadiene (1) and 2,3-bis(tert-butyldimethylsi loxy)butadiene (2) have been homopolymerized and copolymerized with st yrene (St) and methyl methacrylate (MMA) under free-radical conditions . Comparison of initial rates and molecular weights with polymerizatio ns conducted under identical experimental conditions on monosubstitute d analogs, 2-trimethysiloxybutadiene (3) and 2-(tert-butyldimethylsilo xy)butadiene (4), demonstrated that the second substituent does not de crease the polymerizability significantly despite the additional steri c hindrance introduced in the monomer. Extensive H-1 and C-13 NMR char acterization of the polymers demonstrated that the main incorporation mode is of the 1,4-type, allowing more than 95% of the butadienyl subu nit to be incorporated in the main chain as an alpha,beta-bis(trialkyl siloxy)vinylene functional group. Monomer reactivity ratios r(1) and r (2) at 60 degrees C were determined from copolymer composition curves obtained at low conversions and are compared with values obtained for other 1,2-butadienyl systems.