Fabrication of Thermally Conductive Textiles with Oriented Hexagonal Boron Nitride Nanosheets via Aligned Cellulose Nanocrystals

Driven by the need for personal thermal management, high-thermal-conductivity textiles are increasingly sought after. Herein, we report the fabrication of highly thermally conductive and flexible composite fibers. Boron nitride nanosheets (BNNS) were modified with cellulose nanocrystals (CNC) via Lewis acid–base interactions. Composite fibers (CPBNPF) were then prepared by wet-spinning polyurethane (PU) with functionalized fillers. A posttreatment involving hot drawing and hot pressing was employed to align the fillers, producing BNNS oriented composite fibers (CPBNPF-H). At a filler loading of 60 wt % and a draw ratio of 100%, the optimal fiber (CPBNPF-H-2) achieved a through-plane thermal conductivity of 0.49 ± 0.02 W/mK. This represents an enhancement of approximately 444% over PU, which is attributed to the highly aligned BNNS network. Furthermore, fabrics woven from these fibers demonstrated excellent durability, retaining their thermal conductivity after 1000 twisting/bending cycles and 20 washing cycles. This work provides an effective strategy for designing multifunctional composites with great potential for intelligent thermal-regulating textiles.