Evaluation of Organically Modified Layered Double Hydroxides as Fillers for the Preparation of Polymer Nanocomposites in Miniemulsion Polymerization

摘要

Latexes of poly(n-butyl acrylate-co-methyl methacrylate) [P(BA-co-MMA)] filled with magnesium-aluminum layered double hydroxides (MgAl-LDHs) are synthesized using miniemulsion polymerization. Three commercial LDHs organically modified with different types of anions are used as fillers (Perkalite F100S, Perkalite A100, and Perkalite AF50) and three different types of surfactants are tested to stabilize the miniemulsions including a cationic, an anionic, and a nonionic one. Stable LDH-containing miniemulsions are prepared with a mixture of sodium dodecyl sulfate and Triton X-405 and the polymerizable co-stabilizer octadecyl acrylate. They are then polymerized to yield nanocomposite latexes. Depending on the type of LDH used, the presence of the inorganic material in the reaction medium affects the polymerization kinetics. X-ray diffraction analysis of the resulting nanocomposite films suggests exfoliation of the inorganic material. The glass transition temperature of the nanocomposites is not affected by the LDHs and the decomposition temperature of the nanocomposites determined by thermogravimetric analysis is greater than that of the pure polymer.