SYNTHETIC APPROACHES TOWARDS NEW POLYMER SYSTEMS BY THE COMBINATION OF LIVING CARBOCATIONIC AND ANIONIC POLYMERIZATIONS

This study summarizes recent efforts to obtain by combination of livin g carbocationic and anionic polymerizations block copolymers which are potential precursors for building new well-defined polymeric architec tures with microphase separated morphology. Living carbocationic polym erization (LCCP) yields telechelic polyisobutylene (PIB) chains with a variety of useful endgroups, such as tert-chlorine, isopropenyl, prim ary hydroxyl, tolyl etc. When tolyl-ended PIB was used as precursor fo r macroinitiator of living anionic polymerization of 2-(tert-butyldime thylsilyloxy)ethyl methacrylate (tBuM(2)SiOEMA), mixtures of homopolym ers and block copolymers were formed due to incomplete lithiation of t his chain end. In another approach a new functionalization method was developed by end-quenching living PIB chains with 1,1-diphenylethylene (DPE). In the presence of BCl3 a new telechelic PIB with 2,2-diphenyl vinyl (DPV) endgroups was formed. A corresponding DPV model compound w as synthesized from 2-chloro-2,4,4-trimethylpentane (TMPCl). Because o f steric hindrance less than quantitative lithiation of this material occurred. Controlled deprotection of PtBuMe(2)SiOEMA obtained by livin g anionic polymerization (LAP) was utilized to prepare a precursor net work composed of partially deprotected PtBuMe(2)SiOEMA and hydroxyl-te lechelic PIB by using a diisocyanate crosslinker. After network format ion deprotection with HCl was completed and a new amphiphilic network (APN) containing PIB and poly(2-hydroxyethyl) methacrylate) (PHEMA) se gments crosslinked by urethane linkages was obtained.