Synthesis and Characteristics of Poly(methacrylic acid-co-N-isopropylacrylamide) Thermosensitive Composite Hollow Latex Particles and Their Application as Drug Carriers

In this work, the poly(methacrylic acid-co-N-isopropylacrylamide) thermosensitive composite hollow latex particles was synthesized by a three-step reaction. The first step was to synthesize the poly(methyl methacrylate-co-methacrylic acid) (poly(MMA-MAA)) copolymer latex particles by the method of soapless emulsion polymerization. The second step was to polymerize methacrylic acid (MAA), N-isopropylacrylamide (NIPAAm), and N,N-methylenebisacrylamide in the presence of poly(MMA-MAA) latex particles to form the linear poly(methyl methacrylate-co-methacrylic acid)/crosslinking poly(methacrylic acid-co-N-isopropylacrylamide) (poly(MMA-MAA)/poly(MAA-NIPAAm)) core-shell latex particles. In the third step, the core-shell latex particles were heated in the presence of ammonia solution to form the crosslinking poly(MAA-NIPAAm) thermosensitive hollow latex particles. The morphologies of poly(MMA-MAA)/poly(MAA-NIPAAm) core-shell latex particles and poly(MAA-NIPAAm) hollow latex particles were observed. The influences of crosslinking agent and shell composition on the lower critical solution temperature of poly(MMA-MAA)/poly(MAA-NIPAAm) core-shell latex particles and poly(MAA-NIPAAm) hollow latex particles were, respectively, studied. Besides, the poly(MAA-NIPAAm) thermosensitive hollow latex particles were used as carriers to load with the model drug, caffeine. The effect of various variables on the amount of caffeine loading and the efficiency of caffeine release was investigated. (c) 2013 Wiley Periodicals, Inc.