Synergistic Effects of Thermally Induced Gradient Wettability and Pore Structure in Thermoresponsive Polymer-Functionalized Polyester Knitted Fabrics for Adaptive Thermal and Moisture Regulation

Adaptive thermal and moisture regulation was essential for intelligent textile systems designed to enhance personal comfort. In this work, the upper critical solution temperature (UCST)-type thermoresponsive polymer, poly(N,N-dimethyl(methacryloylethyl) ammonium propanesulfonate) (PDMAPS), was deposited onto polyester knitted fabrics via single-sided spray coating and UV-initiated in situ polymerization. The resulting UCST fabrics exhibited a thermally induced gradient system comprising asymmetric surface wettability and temperature-responsive pore structures, driven by the synergistic interplay between the polymer phase transition and knitted loop geometry. Below the UCST (28-30 °C), the thermoresponsive polymer remained in a hydrophobic state, resulting in reduced pore openness and limited heat and moisture transport, thus enhancing thermal insulation, with a surface temperature 4.5 °C higher than that of unmodified fabric. Above the UCST, the UCST polymer transitioned to a hydrophilic state, increasing pore openness and establishing a wettability gradient, facilitating unidirectional moisture transport and effective heat dissipation, with surface temperatures 1.6 °C lower and water vapor transmission rates reaching 8925.69 g·m^-2·d^-1 at 40 °C and 50%RH. The thermoresponsive behavior was reversible over multiple thermal cycles and demonstrated good durability. These results highlighted the potential of UCST fabrics as dynamic thermal-moisture regulation materials, providing a strategy for next-generation intelligent textiles and wearable systems that adaptively respond to changing environmental and physiological conditions.