Facile synthesis of diphenylethylene end-functional polyisobutylene and its applications for the synthesis of block copolymers containing poly(methacrylate)s

摘要

The convenient synthesis of methoxy-free 1,1-diphenylethylene end-functionalized polyisobutylene (PIB—DPE) has been accomplished by capping living PIB with 1,4-bis(1-phenylethenyl)benzene, followed by hydride transfer reaction with tributylsilane. The proposed method eliminates the need for methylation of the capped living PIB in which large excess of dimethylzinc must be used, resulting in a large amount of inorganic salt contamination. The obtained PIB—DPE was quantitatively lithiated with 1.5-fold excess n-butyllithium in tetrahydrofuran (THF) at room temperature. The methine proton at the chain end remained intact during the lithiation procedure. The resulting macroanion efficiently initiated the polymerization of alkyl methacrylates. Poly(methyl methacrylate) (PMMA)-b-PIB-b-PMMA, poly(2-hydroxyethyl meth-acrylate) (PHEMA)-b-PIB-b-PHEMA and poly(tert-butyl mefhacrylate) (P~tBMA)-b-PIB-fo-P'BMA have been prepared with high blocking efficiency by the proposed methodology. Complete hydrolysis of P~tBMA-b-PIB-b-P~tBMA into poly(mefhacrylic acid) (PMAA)-b-PIB-b-PMAA was realized in THF/1,4-dioxane, as confirmed by FTIR, ~1H NMR, and DSC analyses.