Synthesis of well-defined dendritic hyperbranched polymers by iterative methodologies using living/controlled polymerizations

摘要

This review presents firstly the synthesis of various dendritic hyperbranched polymers with well-defined structures by generation-based growth methodologies using living/controlled polymerization.Secondly,the synthesis of dendritic hyperbranched poly(methyl methacrylate)s(PMMAs)and their functionalized block copolymers using a novel iterative methodology is described.The methodology involves a two-reaction sequence in each iterative process:(a)a linking reaction of alpha-functionalized living anionic PMMA with tert-butyldimethylsilyloxymethylphenyl(SMP)groups with benzyl bromide(BnBr)-chain-end-functionalized polymer and(b)a transformation reaction of the SMP groups into BnBr functions.This reaction sequence is repeated several times to construct high-generation(maximum seventh generation)dendritic hyperbranched polymers.Similar branched architectural block copolymers have also been synthesized by the same iterative methodology using other alpha-functionalized living anionic polymers.Surface structures of the resulting dendritic hyperbranched block copolymers composed of PMMA and poly(2-(perfluorobutyl)ethyl methacrylate)segments have been characterized using X-ray photoelectron spectroscopy and contact angle measurements.Solution behaviors of dendritic hyperbranched PMMAs with different generations and branch densities are discussed based on their intrinsic viscosities,g'values and R_h values.