Dimensionally Stable Nanofibrous Nonwoven as a Flexible Dynamic Emissivity Switching Temperature-Regulating Material

Smart textiles that passively regulate thermal comfort provide a sustainable alternative to energy-intensive climate control. A promising strategy involves modulating radiative heat transfer by dynamically adjusting surface emissivity, thereby facilitating reversible switching between heat-retentive and heat-dissipative states. Existing systems enable emissivity switching but often need external energy or lack dimensional stability when deformed, which limits wearable applications. Here, a fully passive, autonomously adaptive dynamic emissivity switch textile (DEST) based on a thermo- and humidity-responsive electrospun poly(N-isopropyl acrylamide) (PNIPAM) copolymer is introduced. To ensure robust functionality in humid or aqueous environments, a crosslinkable allyl-functionalized PNIPAM copolymer is synthesized via post-polymerization amidation of a P(NIPAM-co-methyl acrylate) copolymer and processed using a green water-ethanol-based electrospinning technique. Thiol-ene crosslinking produced water-stable, thermoresponsive nanofibers with a transition near skin temperature. For reversible macropore actuation, a dimensionally stable architecture is employed that avoids out-of-plane distortion, achieved through a honeycomb-shaped electrospinning collector and a tailored mechanical cutting pattern. A silver coating imparts the overall infrared (IR) reflectivity, facilitating radiative heat retention when the macropores are closed. The resulting DEST exhibits dual responsiveness to temperature and ambient humidity, enabling passive switching between emissive and reflective states without external energy input, with a ≈6 °C reversible thermal comfort window.