Unraveling the Influence of Phytic Acid-Modified Boron Nitride Nanosheets as a Sustainable Multifunctional Nanofiller for Poly(3-hydroxybutyrate)

Biodegradable polymers such as poly(3-hydroxybutyrate) (PHB) have emerged as promising green alternatives to conventional petroleum-based plastics. However, their widespread application remains limited due to inherent drawbacks. In this study, we report the application of a sustainable multifunctional nanofiller for the performance enhancement of PHB. The nanofiller is prepared by functionalizing boron nitride nanosheets (f-BNNSs) with biobased phytic acid using a silane coupling agent. A comprehensive investigation was carried out to assess the influence of f-BNNSs on the structural and functional properties of PHB. The incorporation of f-BNNSs exhibited a pronounced nucleating effect, significantly enhancing the crystallization rate of PHB even at a low filler content (1 wt %). The crystallization half-time decreased sharply from 7 min (neat PHB) to 0.8 min at 120 °C with 1 wt % f-BNNSs. The flame-retardant behavior of the nanocomposites was notably improved, primarily due to the synergistic effect of BNNSs, phytic acid, and the silane coupling agent, which also enhanced char-forming ability. Furthermore, the nanocomposites demonstrated superior thermal stability, thermal conductivity, and tensile strength, attributed to strong interfacial interactions between the PHB matrix and f-BNNSs. Moreover, the nanocomposite films demonstrated exceptional oxygen barrier properties, with a 99% reduction in oxygen transmission rate at a filler content as low as 1 wt %. Overall, the multifunctional performance of the f-BNNSs-reinforced PHB nanocomposites highlights their potential as environmentally friendly materials for advanced and sustainable applications.