Successive SET-LRP and ATRP synthesis of ferrocene-based PPEGMEA-g-PAEFC well-defined amphiphilic graft copolymer

摘要

A series of ferrocene-based well-defined amphiphilic graft copolymers, consisting of hydrophilic poly[poly(ethylene glycol) methyl ether acrylate] (PPEGMEA) backbone and hydrophobic poly(2-acryloyloxyethyl ferrocenecarboxylate) (PAEFC) side chains were synthesized by successive single-electron-transfer living radical polymerization (SET-LRP) and atom transfer radical polymerization (ATRP). The backbone was prepared by SET-LRP of PEGMEA macromonomer, and it was then treated with lithium di-isopropylamide and 2-bromopropionyl bromide at -78 °C to give PPEGMEA-Br macroinitiator. The targeted well-defined graft copolymers with narrow molecular weight distributions (M _w/M _n ≤ 1.32) were synthesized via ATRP of AEFC initiated by PPEGMEA-Br macroinitiator, and the molecular weights of the backbone and side chains were both controllable. The electro-chemical behaviors of graft copolymers were studied by cyclic voltammetry, and it was found that graft copolymers were more difficult to be oxidized, and the reversibility of electrode process became less with raising the content of PAEFC segment. The effects of the preparation method, the length of hydrophobic PAEFC segment, and the initial water content on self-assembly behavior of PPEGMEA-g-PAEFC graft copolymers in aqueous media were investigated by transmission electron microscopy. The morphologies of micelles could transform from cylinders to spheres or rods with changing the preparation condition and the length of side chains.