Abstract
Abstract : Diblock copolymers of isotactic polystyrene and 1,4 polybutadiene were successfully synthesized by two methods: a) coupling of two endfunctionalized homopolymers, and b) sequential synthesis of the two blocks. The polybutadiene blocks were prepared by anionic synthesis yielding = 90% 1,4 (cis-trans) and = 10% 1,2 addition. The preparation of the isotactic polystyrene block involved a novel anionic polymerization technique using low temperatures and the addition of BuOLi for stereospecific placement. Overall isotactic yields of 10% by weight were obtained, the remainder being unreacted monomer (50%) and atactic material (40%). The polymers were characterized by GPC, NMR and DSC to determine molecular weights, tacticity and percent crystallinity. The block-like nature of the copolymer was further analyzed through transmission electron microscopy.
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