Multifunctional and robust polyhydroxyalkanoate nanocomposites with superior gas barrier, heat resistant and inherent antibacterial performances

Bio-based and biocompatible materials such as polyhydroxyalkanoates (PHA) suffer from severe bacterial infection, poor oxygen barrier, low strength and poor heat resistance that restrict their wide applications especially in packaging areas. In this work, high-performance PHA nanocomposites with antibacterial properties are successfully obtained by compounding PHA with tailor-made long alkyl chain quaternary salt (LAQ) functionalized graphene oxide (GO -g- LAQ). The GO -g- LAQ could disperse in the PHA matrix uniformly and improve the interfacial adhesion between GO and PHA due to the hydrophobic nature of LAQ. As a result, PHA/GO -g- LAQ nanocomposites have the antibacterial rate of 99.9% against Gram-negative and Gram-positive bacteria without any leaching. The oxygen barrier is improved which is suggested by a significantly reduced oxygen permeation. This could be due to the condensed crystal structure of PHA and the impermeable property of GO sheets. The tensile strength and storage modulus at room temperature of the PHA films increased by 60% and 140%, respectively at an optimized concentration of GO-g-LAQ. The heat resistant performance of the PHA nanocomposites was simultaneously improved significantly due to the enhanced crystallization capability. Therefore, the well-designed PHA/GO -g- LAQ nanocomposites could be ideal candidates of functional materials for (food-) packaging applications.