Synthesis and characteristics of poly(methyl methacrylate-methacrylic acid-3,3-(trimethoxysilyl) propyl methacrylate) hollow latex particles and their application to drug carriers

In this study, the hollow latex particle was synthesized by three processes. The first process was to synthesize the poly(methyl methacrylate-co-methacrylic acid) (poly(MMA-MAA)) copolymer latex particles by the method of soapless emulsion polymerization. Following the first process, the second process was to polymerize MMA, MAA, 3,3-(trimethoxysilyl) propyl methacrylate (MPS), and ethylene glycol dimethacrylate in the presence of poly(MMA-MAA) latex particles to form the linear poly(MMA-MAA)/crosslinking poly(MMA-MAA-MPS) core–shell latex particles. In the third process, the core–shell latex particles were heated in the presence of ammonia to form the poly(MMA-MAA-MPS) hollow latex particles. A sufficient heating time and high-heating temperature were necessary for the ammonia to dissolve the linear poly(MMA-MAA) core to form a perfect hollow structure. The crosslinking poly(MMA-MAA-MPS) shell was a barrier for the ammonia to diffuse into the latex particles so that the latex particle with the high-crosslinking shell showed an imperfect hollow structure. Besides, the hollow poly(MMA-MAA-MPS) latex particles reacted with ZnO nanoparticles, which were synthesized by a traditional sol-gel method, to form the polymer/inorganic poly(MMA-MAA-MPS)/ZnO composite hollow latex particles. With the increase of crosslinking degree would increase the amount of ZnO bonding. Moreover, the poly(MMA-MAA-MPS) hollow latex particles were used as carriers to load with the model drug, caffeine. The release of caffeine from poly(MMA-MAA-MPS) hollow latex particles was investigated.