Synthesis and characteristics of poly( N ‐isopropylacrylamide‐ co ‐methacrylic acid)/Fe 3 O 4 thermosensitive magnetic composite hollow latex particles

In this study, the poly(NIPAAm–MAA)/Fe 3 O 4 hollow latex particles were synthesized by three steps. The first step was to synthesize the poly(methyl methacrylate‐ co ‐methylacrylate acid) (poly(MMA‐MAA)) copolymer latex particles by the method of soapless emulsion polymerization. Following the first step, the second step was to polymerize N ‐isopropylacrylamide (NIPAAm), MAA, and crosslinking agent ( N,N '‐methylene‐bisacrylamide (MBA)) in the presence of poly(MMA‐MAA) latex particles to form the linear poly(MMA‐MAA)/crosslinking poly (NIPAAm‐MAA) core‐shell latex particles. After the previous processes, the core‐shell latex particles were heated in the presence of NH 4 OH to dissolve the linear poly(MMA‐MAA) core in order to form the poly(NIPAAm‐MAA) hollow latex particles. In the third step, Fe 2+ and Fe 3+ ions were introduced to bond with the COOH groups of MAA segments in the poly(NIPAAm‐MAA) hollow polymer latex particles. Further by a reaction with NH 4 OH and then Fe 3 O 4 nanoparticles were generated in situ and the poly(NIPAAm‐MAA)/Fe 3 O 4 magnetic composite hollow latex particles were formed. The concentrations of MAA, crosslinking agent ( N,N '‐methylene bisacrylamide), and Fe 3 O 4 nanoparticles were important factors to influence the morphology of hollow latex particles and lower critical solution temperature of poly(NIPAAm–MAA)/Fe 3 O 4 magnetic composite hollow latex particles. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012