Cellulose nanofibers-enabled interfacial engineering for thermally conductive composites with superior mechanical durability

Cellulose nanofibers (CNFs), derived from renewable biomass, offer exceptional mechanical properties, a high aspect ratio, and abundant surface hydroxyl groups, making them highly attractive for polymer composite functionalization. In this study, CNFs are employed as both dispersing and reinforcing agents to address the dual challenges of filler aggregation and poor interfacial adhesion in nylon-based thermally conductive composites. By leveraging their strong hydrogen bonding capability, CNFs not only enable the uniform dispersion of boron nitride (BN) fillers in aqueous systems but also facilitate the construction of robust interfacial networks within the polymer matrix. Using a simple vacuum-assisted filtration and compression molding strategy, we fabricated laminated composites featuring highly aligned BN structures. This unique architecture promotes the formation of efficient thermal pathways, resulting in an in-plane thermal conductivity of 4.5 Wm⁻¹K⁻¹ at 24.5 wt% BN—an 1857 % enhancement over pure nylon. Simultaneously, the CNF-induced interfacial reinforcement leads to excellent mechanical strength and fatigue resistance, with the composite retaining 92 % of its thermal conductivity and 85 % of its tensile strength after 100,000 bending cycles. These findings demonstrate the significant potential of CNF-assisted interfacial engineering for developing high-performance, thermoplastic-based thermal management materials suitable for flexible electronics and other advanced applications.