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Block Copolymers between Styrene and Isobutylene by a Direct Route

The possibility of synthesizing two- or three-block copolymers between styrene and isobutylene via a direct cationic polymerization has been investigated. Previous studies had shown that the polymerization of these monomers with syncatalytic systems composed of aluminium organic compounds and chlorine are affected by transfer reactions, whereas terminations are almost absent. However, preliminary experiments have shown that the production of two- and three-block copolymers can be achieved to some extent, provided that appropriate experimental conditions leading to a substantial limitation of the importance of transfer reactions are adopted. A mathematical model has been developed which describes satisfactorily the polymerization pattern. This model is being used to determine, with the aid of a computer, the most convenient conditions for the production of block copolymers.