Self-assembly of Gradient Copolymer Synthesized by Spontaneous Batch RAFT Emulsion Polymerization and Its Application on Encapsulating Ag Nanoparticles

Abstract

The gradient copolymers of acrylic acid and trifluoroethyl methacrylate (coded as P(TFEMA-grad-AA)) were synthesized via reversible addition-fragmentation transfer (RAFT) emulsifier-free emulsion polymerization. The spontaneous batch feeding approach was used to control the gradient chain sequence. Transmission electron microscopy (TEM) analysis revealed that the P(TFEMA-grad-AA) can self-assemble to form spherical micelles, rodlike micelles or vesicles in selective solvents. Morphological transition of the P(TFEMA-grad-AA) micelles was sensitive to the water content of the dioxane/water mixed solvent. More interestingly, Ag nanoparticles (NPs) were encapsulated by the P(TFEMA-grad-AA) micelles during the self-assembly process. The gradient chain sequence made the Ag NPs easily enter the core of the micelles, even when P(TFEMA-grad-AA) had less hydrophobic fluoro-units and more hydrophilic units. TEM images with energy dispersive spectrometer indicated that the nanocomposite micelles consisted of a Ag NPs core and a gradient copolymer shell.

Keywords

gradient copolymer / self-assembly / encapsulation / RAFT emulsion polymerization / spontaneous batch feeding