The Preparation of Amphiphilic Core-Shell Nanospheres by Using Water-Soluble Macrophotoinitiator

The amphiphilic poly(AM-co-SA)-ITXH macrophoto-initiator was synthesized by precipitation photopolymerization under UV irradiation with isopropylthioxanthone (ITX) as free radical photoinitiator. A novel method has been developed to prepare amphiphilic core-shell polymer nanospheres via photopolymerization of methyl methacrylate (MMA) in aqueous media, with amphiphilic copolymer macrophotoinitiator poly(AM-co-SA)-ITXH. During polymerization, the amphiphilic macroradicals underwent in situ self-assembly to form polymeric micelles, which promoted the emulsion polymerization of the monomer. Thus, amphiphilic core-shell nanospheres ranging from 70 to 140 nm in diameter were produced in the absence of surfactant. The conversion of the monomer, number average molecular weights (M-n), and particle size were found to be highly dependent on the macrophotoinitiator and monomer concentration. The macrophotoinitiator and amphiphilic particles were characterized by FTIR, UV-vis, H-1 NMR, TEM, DSC, and contact angle measurements. The results showed the particles had well-defined amphiphilic core-shell structure. This new method is scientifically and technologically significant because it provides a commercially viable route to a wide variety of novel amphiphilic core-shell nanospheres. (C) 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48:936-942,2010