Paper, for writing and printing, is consumed a lot in modern life. However, the production of conventional paper could cause many problems, such as deforestation and environmental pollution. Therefore, it is necessary and urgent to explore novel strategies to solve these problems. In this work, a polyoxometalate-doped gelatin film with high strength, excellent transparency, and fast photochromic properties is designed and prepared. The film can display different colors by using a variety of reagents, exhibiting its potential application as a paper medium. Its rapid photochromic properties allow complex high-resolution images to be displayed by UV light printing. It is found that the mechanical and photochromic properties could be regulated by the introduction of triethylene glycol, and the fading process could be controlled by changing the temperature and humidity. Moreover, it is rewritable, self-repairable, and recyclable, and can also achieve long-term preservation without fading. It is envisioned that the environmentally friendly films with low cost, ease of preparation, and recycling advantages have the potential to be an alternative to conventional paper for writing and printing.
Keywords: gelatin; light printing; photochromism; polyoxometalate; rewritable paper.