Photoresponsive Electrospun Nanowire Films Based on N-Isopropylacrylamide and Spiropyran for Regulating Microenvironmental Humidity

Based on the goal to improve the humidity index of the microenvironment and enhancing human comfort, this study used electrospinning to prepare several photoresponsive films with reversible regulation of wettability and microenvironmental humidity from copolymers of acrylated spiropyran (SPA), N-isopropylacrylamide (NIPAm), and methyl methacrylate (MMA). According to the photoisomerization mechanism of spiropyran, the simple ultraviolet (UV)–visible light (vis) reversible light radiation change makes the spiropyran unit switch between the polar ring-opened form and the nonpolar ring-closed form. Utilizing this transition can easily regulate the wettability of the film surface and microenvironmental humidity. The experimental results show that poly(SPA1-co-NIPAm2-co-MMA8) nanowire film has the best ability to regulate wettability and humidity; the wettability can vary within a range of 13° and the microenvironmental humidity up to 7.2%.