Synthesis of Controlled Block and Graft Copolymers. I. Block-Polymerizations Initiated Asymmetric Telechelic Bromo-Terminated Polymer Together with Manganese Carbonyl

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Abstract
Various types of halogen-terminated polymers having different backbones were synthesized and used as polymeric initiators together with manganese carbonyl for block polymerizations. The number of end groups and the molecular weights of the polymeric initiators could be varied by adjusting the feed composition and the transfer agent. Block polymerizations of methyl methacrylate and styrene with these telechelic bromo-terminated polymers-manganese carbonyl initiator systems were carried out photochemically at 30°C and in the dark at 80°C. It was found that the dark polymerization with the initiator system at 80°C provided excellent conditions to control the length of the blocks. Polymerization of methyl methacrylate initiated by manganese carbonyl together with carbon tetrabromide as a model compound of the polymeric initiator was also investigated. Block-forming efficiencies of these block polymerizations were estimated to range from 96 to 99%. The number-average degree of polymerization of blocks of the second monomer obtained by use of the telechelic bromo-terminated backbone polymer as polymeric initiator could be controlled by adjusting the amount of the second monomers and the polymeric initiator/manganese carbonyl ratio.