Weldable and calligraphy programmable humidity-actuated regenerated cellulose film from waste cotton fabric

The textile industry has caused significant pollution and resource consumption. To address the issue of textile waste, it is crucial to effectively recycle most common natural fiber - cotton. However, current methods face limitations in terms of cost and efficiency. In this study, we developed a weldable and programmable humidityactuated regenerated cellulose (RC) film based on discoloration, dissolution, regeneration, and vacuum filtration of cotton textiles waste. Therein, the dissolution of cotton waste by phosphoric acid (PA) offers advantages of high efficiency, low cost, and mild dissolution conditions. Especially, we proposed a water-assisted welding process to connect independent films, allowing for the design of a smart cuff with adjustable flaps showing the potential for improved thermal-moisture comfort. Furthermore, inspired by Chinese calligraphy, a hydrophobicity programming strategy is introduced, facilitating diverse actuation and the creation of an information encryption device. Overall, this work shows promise for efficient, cost-effective recycling and intelligent application of cotton textiles waste. The proposed water-assisted welding and calligraphy-inspired programming would pave the way to advance multiscale, adaptive, and intelligent actuation of cellulose materials.