Boron nitride as a functional filler in biodegradable polymers: structure-property correlations and performance

Two-dimensional layered materials have brought significant attention as reinforcement nanofillers in biodegradable polymers, with hexagonal boron nitride (h-BN) emerging as a promising candidate due to its unique combination of exceptional properties and broad application potential. This review systematically examines the structure-property relationship in boron nitride-based polymer nanocomposites, highlighting the influence of h-BN incorporation in biodegradable polymer matrices. Particular emphasis is given on the exfoliation techniques of h-BN, with liquid-phase exfoliation identified as the most widely used method for obtaining few-layered boron nitride nanosheets. The influence of key factors, such as nanofiller morphology, dispersion within the polymer matrix, and interfacial interactions, on the overall performance of the nanocomposite is thoroughly analysed. In particular, strategies that combine concurrent surface functionalisation and exfoliation are discussed as effective routes to enhance interfacial compatibility, thereby improving the nanocomposite properties. Notably, even low filler loadings can significantly affect the crystallisation behaviour, thermal conductivity, mechanical property, gas barrier performance, flame retardancy, piezoelectric response, and optical characteristics of biodegradable polymers. Overall, this review consolidates the design of high-performance h-BN-reinforced biodegradable polymer nanocomposites, highlighting their potential across a range of applications.