Chemists at the University of California, Riverside, have developed a novel rewritable and reusable paper.

The rewritable paper is essentially rewritable media in the form of glass or plastic film to which letters and patterns can be repeatedly printed, retained for days, and then erased by simple heating, according to reports from the University of California.

The reusable paper is based on the colour switching property of commercial chemicals called redox dyes. The dye forms the imaging layer of the paper. Printing is achieved by using ultraviolet light to photobleach the dye, except the portions that constitute the text on the paper.

During the writing phase, ultraviolet light reduces the dye to its colourless state. During the erasing phase, re-oxidation of the reduced dye recovers the original colour; that is, the imaging material recovers its original colour by reacting with ambient oxygen.

Professor Yadong Yin, whose chemistry lab led the research said, “The rewritable paper does not require additional inks for printing, making it both economically and environmentally viable. It represents an attractive alternative to regular paper in meeting the increasing global needs for sustainability and environmental conservation.”

The research was funded by a grant to Yin from the US Department of Energy. The lab is also working on increasing the number of times the rewritable paper can be printed and erased, with a target of 100, to reduce the overall cost. The research team is exploring ways to extend the legibility of the printed texts or images for more than three days to expand their potential uses. (GK)