Ultrasound-assisted synthesis of poly(MMA-co-BA)/ZnO nanocomposites with enhanced physical properties

The present study reports synthesis and characterization of poly(MMA-co-BA)/ZnO nanocomposites using ultrasound -assisted in-situ emulsion polymerization. Methyl methacrylate (MMA) was copolymerized with butyl acrylate (BA), for enhanced ductility of copolymer matrix, in presence of nanoscale ZnO particles. Ultrasound generated strong micro-turbulence in reaction mixture, which resulted in higher encapsulation and uniform dispersion of ZnO (in native form-without surface modification) in polymer matrix, as compared to mechanical stirring. The nanocomposites were characterized for physical properties and structural morphology using standard techniques such as XRD, FTIR, particle size analysis, UV-Visible spectroscopy, electrical conductivity, TGA, DSC, FE-SEM and TEM. Copolymerization of MMA and BA (in presence of ZnO) followed second order kinetics. Thermal stability (T-10% = 324.9 degrees C) and glass transition temperature (T-g = 67.8 degrees C) of poly(MMA-co-BA)/ZnO nanocomposites showed significant enhancement (35.1 degrees C for 1 wt% ZnO and 15.7 degrees C for 4 wt% ZnO, respectively), as compared to pristine poly(MMA-co-BA). poly(MMA-co-BA)/ZnO (5 wt%) nanocomposites possessed the highest electrical conductivity of 0.192 mu S/cm and peak UV absorptivity of 0.55 at 372 ma. Solution rheological study of nanocomposites revealed enhancement in viscosity with increasing ZnO loading. Maximum viscosity of 0.01 Pa-s was obtained for 5 wt% ZnO loading.