Sonochemical Synthesis of Poly(lactic acid) Nanocomposites with ZnO Nanoflowers: Effect of Nanofiller Morphology on Physical Properties

This study reportsthe ultrasound-assisted synthesis of PLA/ZnOnanocomposites with the special feature of a flower-like morphologyof ZnO. The ZnO nanoflowers were synthesized via a facile sonochemicalmethod with Zn-(NO3)(2)& BULL;6H(2)O asprecursor in different concentrations of 0.025, 0.05, 0.075, and 0.1M. The as-synthesized ZnO had a flower-like morphology with petalsof thickness & AP; 21 nm, width in the range of 200-800nm, and total BET surface area of 19.87 m(2) g(-1). Films of PLA/ZnO nanocompositeswere synthesized with an ultrasound-assisted solution casting method.Characterization of the nanocomposites revealed excellent thermal,optical, and mechanical properties at a very low loading of ZnO (0.5wt %): tensile strength = 26-32 MPa, % elongation = 2.9 to4.7%, highest degradation temperature = 298 & DEG;C, glass transitiontemperature = 52 & DEG;C, reduction in UV transmittance (absorptionedge 368 nm) = 95%. In addition, PLA/ZnO nanocomposite films possessedefficient antimicrobial properties with >99% reduction of bothGram-negativeand Gram-positive bacteria (Escherichia coli and Listeria. monocytogenes) in just 12 to 18 h. These propertiesare attributed to high interfacial interactions between nanofillerand the PLA matrix resulting from special morphological features ofZnO nanoflowers, and also uniform dispersion of ZnO nanoflowers inthe PLA matrix under the influence of sonication.