Emulsion and nanocapsules of ternary graft copolymers

Abstract

Alkyne end-tagged poly(ethylene glycol) methyl ether, polystyrene, and poly(tert-butyl acrylate) (denoted as MPEG–CCH, PS–CCH, and PtBA–CCH, respectively) were grafted randomly onto a (PGMA–N₃) backbone via “click” chemistry to produce a series of ternary graft copolymers PGMA-g-(MPEG-r-PtBA-r-PS). The selective hydrolysis of the PtBA chains into poly(acrylic acid) (PAA) yielded PGMA-g-(MPEG-r-PAA-r-PS). Since MPEG and PAA were soluble in water while PS was soluble in decahydronaphthalene (DN), the graft copolymers were good surfactants for emulsifying DN in water. Various factors affecting the emulsification were examined, including the stirring rate, the copolymer composition, and the concentration. Crosslinking of the PAA chains, which were distributed among MPEG chains in the coronas of the emulsion droplets, with a diamine produced a novel structure – “nanocapsules” bearing partially crosslinked coronas.