Shape-Controlled Poly(N-isopropylacrylamide) Actuators Enabled by Tensile-Stress Mismatch for Temperature-Adaptive Textiles

Abstract

Thermal comfort is a key determinant of human health and requires adaptive responses to dynamic environments. Here, we report a temperature-adaptive textile enabled by a tensile stress mismatch-driven poly(N-isopropylacrylamide) (PNIPAM) actuator operating within a human-friendly temperature range of 18–38 °C. A pre-stretched polyurethane core fiber integrated within a PNIPAM sheath in a noncoaxial configuration induces programmable bending through tensile-stress mismatch between elastic recovery and hydrogel swelling. Unlike conventional bilayer hydrogel actuators based on differential swelling between laminated layers, this pre-stretching strategy amplifies structural deformation through elastic restoring stress. When extended to a two-dimensional textile architecture, this strategy enables reversible, dynamic pore modulation with an approximately 400% increase in pore area. This study provides a promising platform for smart adaptive textiles, wearable healthcare, and soft robotics.