Efficient one-pot synthesis of uniform, surface-functionalized, and “living” polymer microspheres by reverse atom transfer radical precipitation polymerization

Abstract

A facile, general, and efficient one-pot approach to obtain uniform, highly cross-linked, surface-functionalized, and “living” polymer microspheres by reverse atom transfer radical precipitation polymerization (RATRPP) is described for the first time, which is easily realized by introducing reverse atom transfer radical polymerization (reverse ATRP) mechanism into precipitation polymerization system. The polymerization parameters including stirring rate, polymerization temperature, monomer loading, initiator concentration, and polymerization scale and time showed considerable influence on the yields and morphologies of the polymer microspheres, which makes it convenient to tailor the particle sizes by tuning polymerization conditions. The general applicability of RATRPP was verified by preparing some uniform functional copolymer microspheres with incorporated 4-vinylpyridine, glycidyl methacrylate, and 2-hydroxyethyl methacrylate. Moreover, the resulting polymer microspheres proved to be “living” by their direct grafting of hydrophilic polymer brushes via surface-initiated ATRP. Furthermore, a mixed particle growth mechanism is proposed for RATRPP (i.e., a combined “grafting from” and “grafting to” mechanism works prior to the consumption of the conventional initiator and a “grafting from” mechanism is dominant afterwards), which is quite different from the “grafting to” particle growth mechanism in the traditional precipitation polymerization and “grafting from” mechanism in the normal ATRPP.