Ternary Graft Copolymers and Their Use in Nanocapsule Preparation

Abstract

Grafting three types of polymer chains onto the backbone of a fourth polymer yielded a ternary graft copolymer. The copolymer dispersed oil droplets in water with one type of graft stretching into the oil phase, the second type forming a thin membrane separating the two phases, and the third type stretching into the water phase. Since the second type was also photo-cross-linkable, shining UV light on the system produced permanent nanocapsules. To produce the graft copolymer, the backbone polymer used was poly(3-azido-2-hydroxypropyl methacrylate), P(GMA-N3). The grafts used were all end-functionalized by alkyne groups, and the polymers were poly(ethylene glycol) methyl ether (MPEG), polystyrene (PS), and poly(2-cinnamoyloxyethyl methacrylate) (PCEMA), respectively. Evidently, MPEG was water-soluble, PS was soluble in the used oil decahydronaphthalene (DN), and PCEMA was photo-cross-linkable and soluble in neither water nor DN. The grafts denoted as MPEG–C≡CH, PS–C≡CH, and PCEMA–C≡CH were coupled to P(GMA-N3) via click chemistry between the azide and alkyne units. Under the used conditions, the one-pot grafting reactions were quantitative.