Enhanced performance of biobased composite films: the role of boron nitride nanoplatelets in tuning their hydrophobic, chemical resistance, thermal and electrical properties

Abstract

The development of sustainable biodegradable polymers or biopolymer-based composites is vital for addressing environmental challenges posed by petroleum-derived materials. However, the practical applications of biopolymers remain constrained by the poor mechanical strength, low chemical stability and poor thermal conductivity. In this study, a multifunctional bio-composite film with excellent mechanical strength and enhanced hydrophobicity was fabricated by incorporating exfoliated boron nitride nanoplates (BNNPs) and cellulose nanofibers (CNFs) into the chitosan (CH) matrix. The influence of BNNP loading on the structural, thermal and surface properties of the film was systematically investigated. Increasing the loading of BNNPs alters the wettability of the resulting films, while significantly enhancing their mechanical strength, thermal stability, and UV shielding performance. At an optimum BNNP loading of 2 wt%, the composite film achieved a tensile strength of 46.3 MPa (an ∼82% increase relative to the CH–CNF film), enhanced hydrophobicity with a contact angle of 117.1° and a thermal conductivity of 0.68 W m⁻¹ °C. The film also demonstrated excellent resistance to acidic and alkaline environments. Structural and morphological analyses confirmed uniform dispersion of BNNPs and strong interfacial interaction with CNFs, promoting effective stress transfer and phonon transport. Furthermore, the bio-composite film displayed sensitivity towards ammonia (NH₃), showing a decrease in resistance as observed in Cole–Cole plots upon exposure to ammonia, depicting improved charge transfer. These findings highlight the synergistic role of BNNPs and CNFs in engineering high-performance, eco-friendly films suitable for packaging, protective coatings, and flexible electronics as well as the film's potential for ammonia sensing applications.