Smart Fiber Materials for Light-Induced Bidirectional Humidity Regulation: Self-Assembly Realizes the Renewable Properties

The balance of microenvironmental humidity affects all aspects of life, for example, in the conservation of cultural heritage and the preservation of books and archives, which require a stable and balanced level of humidity. Therefore, it is vital to develop a material that can regulate the humidity of the microenvironment. The study of the renewable properties of materials has been an important breakthrough in this field toward practical applications. In this study, self-assembly technology has been innovatively applied to the field of regenerative materials for the first time. By bonding spiropyran with the host molecule cyclodextrin and subsequently self-assembling with the guest polymer adamantane, porous materials were successfully prepared using electrospinning technology. Spiropyran undergoes a reversible transition between polar hydrophilic and nonpolar hydrophobic states under alternating UV/visible light irradiation, which is a perfect fit for the design of humidity-regulating materials. Spatial site resistance of β-cyclodextrin played an important role in the efficiency of host–guest binding, which ultimately had a direct impact on the ability of the material to regulate humidity. When the material fails due to prolonged use, disassembly and reassembly of cyclodextrins and adamantanes enable the renewable properties of materials.