Dual responsive macroemulsion stabilized by Y-shaped amphiphilic AB2 miktoarm star copolymers†
Abstract
Dual responsive macroemulsions stabilized by Y-shaped amphiphilic AB2 miktoarm star polymeric emulsifiers were presented in this study. First, a amphiphilic Y-shaped AB2 miktoarm star polymer composed of poly(N,N-dimethylaminoethylmethacrylate) (PDMAEMA) and polystyrene (PS) arms was synthesized by sequential reversible addition–fragmentation chain transfer (RAFT) polymerization of styrene monomer and atom transfer radical polymerization (ATRP) of N,N-dimethylaminoethyl methacrylate (DMAEMA) monomer. The structure and the molecular weight as well as the molecular weight distribution were carefully characterized by 1H NMR and GPC, respectively. The obtained PS–(PDMAEMA)2 miktoarm star polymers were then applied as polymer emulsifiers for both o/w and w/o macroemulsions formation, and stabilized macroemulsions could be produced at a lower emulsifier content. Meanwhile, the emulsifying performance of PS–(PDMAEMA)2 miktoarm star polymer and stimulus-response of the macroemulsion were also investigated. The PS–(PDMAEMA)2 stabilized o/w macroemulsion showed pH-induced demulsification and temperature-induced phase inversion. However, the inversion of the PS–(PDMAEMA)2 emulsifier at the oil–water interface could not be spontaneously accomplished. Furthermore, successful phase inversion was only smoothly realized for those emulsions with pH 7 water in the presence of a modulate stirring.
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