writer：Dong-ming Qi, Yong-zhong Bao, Zhi-xue Weng, Zhi-ming Huang
keywords：Composite particle,nanometer silica, emulsion polymerization, acrylate
source：期刊
specific source：J Appl Polym Sci, 99: 3425-3432
Issue time：2006年

Poly(butyl acrylate)/poly(methyl methacrylate) (PBA/PMMA) core-shell particles embedded with nanometer silica particles, were prepared by emulsion polymerization of butyl acrylate (BA) in the presence of silica particles pre-absorbed with 2,2’-azobis(2-amidinopropane)dihydrochloride (AIBA) initiator, and subsequent MMA emulsion polymerization in the presence of PBA/silica composite particles. The morphology of the resulting PBA/silica and PBA/silica/PMMA composite particles were characterized. It showed that AIBA could effectively be absorbed onto silica particles when the pH value of the dispersion medium was greater than the isoelectric potential point of silica. The critical amount of AIBA added for the stable dispersion of silica particles increased as the pH value of the dispersion medium increased. The PBA/silica composite particles prepared by in-situ emulsion polymerization using silica pre-absorbed with AIBA, showed a higher silica absorption efficiency than the PBA/silica composite particles prepared by direct mixing of PBA latex and silica dispersion, or by emulsion polymerization in which AIBA was added after the mixing of BA and silica. The PBA/silica composite particles exhibit a raspberry-like morphology with silica particles “adhered” onto the surface of PBA particles, while, the PBA/silica/PMMA composite latex particles exhibited sandwich morphology with silica particles mainly located at the interface between the PBA core and the PMMA shell. Subsequently, the obtained PBA/silica/PMMA composite latex had narrow particle size distribution and good dispersion stability.