Preparation of P(BA-MMA-AA)/TiO2 nanocomposites through ultrasonically initiated in situ emulsion polymerization

A new and simplistic method, ultrasonic irradiation technique was employed to prepared poly( n-butyl acrylate-co-methyl methacrylate-co-methacrylic acid)[ P(BA-MMA-AA)]/TiO2 nanocomposites. By taking advantage of the multiple effect of ultrasound, such as dispersion, pulverization, activation and initiation, the aggregates of TiO2 particles can be broken down. The polymerization of monomers BA, MMA, and functional monomer AA proceeded while TiO2 particles were redispersed by ultrasound. The stable P(BA-MMA-AA)MO, nanocomposite emulsion was obtained. The effects of several main factors, such as surfactant concentration, monomers concentration and the amount of TiO2, on polymerization rate were investigated. The experimental results showed that with increase in SDS surfactant concentration and decrease in monomers concentration and the amount of TiO2 the polymerization rate increased. TEM, SEM and FTIR analyses confirmed that polymers were present on TiO2 surface, and there was strong interaction between TiO2 and polymers with carboxylic functional groups. DSC, GPC, H-1-NMR characterizations showed that with the introduction of TiO2, the average molecular weight of the obtained copolymer decreased, molecular weight distribution became wide, and the BA content of copolymer chains increased compared to that of the pure copolymer, resulting in lower T-g. This method has the following advantages, (1) aqueous medium, ( 2) without any additional chemical initiator, (3) lower reaction temperature, usually near ambient temperature, (4) ease of operating and (5) the encapsulated polymer layer can be well designed to meet different requirements.