Dual-Reactive Surfactant Used for Synthesis of Functional Nanocapsules in Miniemulsion

Abstract

Dual-functional amphiphilic block copolymers, alpha-azido-omega-2-chloroisobutyrate-poly(oligo(ethylene oxide) monomethyl ether methacrylate)-b-poly(n-butyl methacrylate), prepared by atom-transfer radical polymerization were used as dual-reactive surfactants (i.e., macroinitiators for a miniemulsion copolymerization of a monovinyl monomer and divinyl cross-linker as well as surfactants with latent functionality). Because of the amphiphilic nature of the block copolymers used as surfactant/initiators, the polymerization was initiated at the oil-water interface, with polymer chains slowly growing inward in a controlled manner after activation by the catalyst. Polymeric nanocapsules with cross-linked shells and the latent azido functionality were obtained. Introduction of various degradable cross-linking agents into the system resulted in the formation of nanocapsules that were cleaved under specific conditions. The preserved latent alpha-terminal azido groups in the dual-reactive surfactant were utilized to attach a fluorescent dansyl probe and/or atom-transfer radical polymerization initiators to grow linear polymer chains forming an additional shell covalently connected to the nanocapsules.