Effects of stirring rate on morphology of aqueous RAFT emulsion PISA-derived block copolymer nanoparticles

Abstract

The influence of stirring rate on nanoparticle morphology in aqueous RAFT emulsion PISA has been investigated using the macroRAFT agents poly(poly(ethylene)glycol methyl ether acrylate)-TTC and poly(poly(ethylene glycol) methyl ether methacrylate)-TTC chain extended with styrene/n-butyl acrylate (copolymer) and methyl methacrylate (MMA), respectively. The influence of temperature was first investigated by conducting polymerizations at 50 °C and 70 °C for the MMA system, revealing that formation of high-order morphologies is facilitated at 70 °C. The influence of stirring rate was explored for both systems, showing that the extent of influence depends on the polymerization temperature. At 50 °C, high-order morphologies were obtained only at moderate stirring rate whereas at 70 °C, high-order morphologies were observed across a much wider range of stirring rates. The present results demonstrate that both polymerization temperature and stirring rate can significantly affect the self-assembly process in PISA.