Intelligent color-changing hygrothermal-controlled film for enhanced thermal comfort of personal protective equipment

The impermeable design of personal protective equipment (PPE) is significant to protect people in specific areas, but this can make it difficult for the body to dissipate heat, triggering heatstroke and health risks. Herein, an intelligent color-changing hygrothermal-controlled film (CHF) is successfully prepared by a simple and low-cost strategy. Adsorption moisture management and evaporative cooling technologies regulate moisture inside garments to reduce body temperature. Since the reversible conversion between [Co(H2O)6]2+ and Co2+ triggers a color change, the humidity-sensitive CHF can intelligently change the color when the humidity is excessively high. After 30 times of adsorption–desorption tests and 150 times of cyclic tensile tests, CHF maintains an excellent stability and reusability. Since the CHF is applied to PPE, the relative humidity decreases significantly from 93.3 % to 50.6 % and the corresponding heat index decreases from 66.2 °C to 40.9 °C, which greatly reduces the possibility of heatstroke of the wearer. The thermal manikin experiment illustrates that the CHF can reduce the evaporation resistance of protective clothing to 15 % of the original value, thus promote the evaporation of sweat from the human body. This work brings a new solution to improve the thermal comfort of PPE.