Synthesis and Characterization of Waterborne Pyrrolidone-Functional Diblock Copolymer Nanoparticles Prepared via Surfactant-free RAFT Emulsion Polymerization

Abstract

Polymerization-induced self-assembly enables the facile synthesis of a wide range of block copolymer nano-objects in the form of concentrated dispersions. In this context, many surfactant-free reversible addition–fragmentation chain transfer (RAFT) aqueous emulsion polymerization formulations have been reported using various nonionic and polyelectrolytic water-soluble precursors for the steric stabilizer block. In the present study, we examine poly(2-(N-acryloyloxy)ethyl pyrrolidone) (PNAEP) as a new nonionic stabilizer block. A trithiocarbonate-based PNAEP precursor with a mean degree of polymerization of 67 was employed as the steric stabilizer for the RAFT emulsion polymerization of styrene, n-butyl acrylate (nBA), or statistical mixtures thereof. The RAFT emulsion polymerization of styrene using a VA-044 azo initiator at 80 °C and pH 7 led to essentially full conversion within 40 min, with induction times as short as 10 min, whereas gel permeation chromatography analysis confirmed efficient chain exte...