Synthetic approaches towards new polymer systems by the combination of living carbocationic and anionic polymerizations

Recent efforts to obtain block copolymers by combination of living carbocationic and anionic polymerizations are presented.When tolyl-ended polyisobutylene was used as macroinitiator of anionic polymerization of methacrylate derivatives mixtures of homopolymers and block copolymers were formed due to incomplete lithiation of this chain end.In another approach a new functionalization method was developed by end-quenching living polyisobutylene with 1,1-diphenylethylene.

After transformation of the groups into 2,2-diphenylvinyl end groups and lithiation polymers were synthesized from protected acrylate monomers. After partial deprotection a network could be formed by reaction with diisocyanate. Complete deprotection yielded a new amphiphilic network containing polyisobutylene and poly(2-hydroxyethyl) methacrylate segments crosslinked by urethane linkages.