Design of a unidirectional water-transport skin-derived wearable material through engineering a natural pore-size gradient for personal wet–thermal management†

Abstract

Unidirectional water-transport wearable materials play a key role in enhancing human comfort by effectively removing excess sweat. However, making unidirectional water-transport wearable materials, other than textiles, remains a challenge. Hence, a novel unidirectional water-transport skin-derived wearable material (UWT-Skin) is skillfully engineered based on a natural pore-size gradient from animal skin. The hydrophilic polyurethane fibrous membrane and hydrophobic polyvinylidene-fluoride coating on both sides of the natural skin derived from animal skin together create a gradient in pore size from macro to sub-micron levels, as well as a hydrophobic-to-hydrophilic gradient across the UWT-Skin. Leveraging the unidirectional capillary force generated by this dual-gradient design, UWT-Skin demonstrates an excellent unidirectional water-transport capability (R) of 731%, independent of gravity and over a wide range of sweat pH values. Gratifyingly, UWT-Skin promotes sweat removal, weakens sticky adhesion, and prevents excessive cooling (maintaining ∼2.0 °C higher than cotton and common N-Skin), thereby providing enhanced personal wet–thermal comfort in hot or humid environments. Additionally, it exhibits outstanding water vapor permeability (3943.5 g (m² 24 h)⁻¹), air permeability (2659.1 mL (cm² h)⁻¹), mechanical properties, softness and colorization, all of which ensure wearability. Overall, the successful development of this natural skin-derived wearables is valuable for evoking the enthusiasm for wearing them in sunny weather and inspires further innovation in natural fiber materials designed to provide personal wet–thermal comfort.