Investigations in two-step ultrasonic synthesis of PMMA/ZnO nanocomposites by in–situ emulsion polymerization

Abstract

Abstract This paper reports two-step ultrasonic method for in-situ synthesis of PMMA/ZnO nanocomposites. First step comprises nanoscale ZnO synthesis through ultrasound-assisted in-situ hydrolysis of zinc acetate. In second step, PMMA/ZnO nanocomposites have been synthesized via ultrasound-assisted in-situ emulsion polymerization in presence of native ZnO particles (1–5 wt%, without surface modification). Approx. 10 × -enhancement in polymerization kinetics is obtained. Properties of nanocomposites for different ZnO loadings are: particle size = 77.7–109.7 nm, maximum degradation temperature = 386.4 °C, maximum glass transition temperature = 122.5 °C, UV–visible absorption band width = 350–375 nm, electrical conductivity = 0.028–0.207 μS/cm, tensile strength = 25.8–36.57 MPa, Young's modulus = 1.09–1.47 GPa, percentage elongation = 10.98–17.56%. These enhanced properties (as compared to previous literature) are essentially attributed to uniform dispersion of ZnO in polymer matrix due to intense micro-convection generated by sonication. This results in strong interfacial interactions and adhesion between phases with increased crystallinity.