Stretchable h-BN/TPU Fibers for Passive-Active Dual-Mode Thermal Management and Wearable Haptic Interfaces.

Wearable thermal interfaces require rapid, spatially confined thermal feedback together with mechanical compliance, yet existing passive thermal-management textiles and active thermal-haptic devices remain largely separate. Here, a stretchable h-BN/TPU composite fiber is developed by coupling microfluidic spinning with non-solvent-induced phase separation. Rectangular-channel confinement aligns hexagonal boron nitride plates within a microporous thermoplastic polyurethane matrix, constructing directional heat-conduction pathways while preserving large deformation. The optimized 30 wt.% h-BN/TPU fiber achieves a dry-state thermal conductivity of 2.08 and 4.14 W·m-1·K-1 under humid conditions, together with 9.67 MPa tensile strength and 422% elongation at break. Pareto-front analysis identifies the 30 wt.% composition as the thermal-mechanical knee, arising from the coupled effects of filler orientation, low void fraction, and deformable TPU domains. Woven h-BN/TPU fabrics provide passive thermal management, reducing surface temperature by 5.7°C under simulated solar irradiation and maintaining performance after 2000 bending cycles. When integrated into a thermal feedback glove, the fabric enables localized fingertip actuation with a heating rate of +29.55°C·s-1 and a thermal relaxation time of ∼20 s (returning below the warm perception threshold of 35°C). This fiber platform bridges passive heat regulation and active thermal haptics for next-generation thermally interactive wearables.