Chemists have developed a new type of paper that can be printed with ultraviolet light. Cheaper and greener, we could then throw away the ink cartridges we are so used to.
In a study published in the scientific journal Nano Letters, a team of researchers led by Wenzhou Wang, from Shandong University in China, researchers from the University of California, Riverside and the Lawrence-Berkeley National Laboratory, announce that they have developed a new simpler, cheaper and more environmentally friendly method of printing that uses the properties of ultraviolet light. The researchers have in fact developed a coating of nanoparticles that can be applied to sheets of paper which changes color in the light of ultraviolet rays. The color change can be reversed when the coating is heated to 120 degrees Celsius, allowing up to 80 rewrites.
How it works ? The secret lies in a chemical phenomenon: the color changes of nanoparticles, a thin layer of which can be applied to basic paper to transform it into this light-printable version. The first layer of nanoparticles is Prussian blue in color. When its number of electrons increases, this layer becomes colorless. As for the second layer, it is made of titanium dioxide, a photocatalytic material that accelerates chemical reactions in response to UV light. Mix these two substances together and you get a blue coating. Add some light UV and in reaction, the titanium dioxide modifies the appearance of the paper which then becomes colorless.
Once the printing process is complete, the paper retains its appearance for five days and then slowly returns to its blue color as it oxidizes under the effect of ambient conditions. To erase the paper faster, it is possible to heat it for ten minutes.
Discovery » could have huge economic and environmental benefits for today’s society as Yadong Yin, professor of chemistry at the University of California, Riverside, explains to Phys.org. The researchers hope that their erasable paper could in particular allow the printing of documents which have only a short-term utility. » We believe that this rewritable paper has many practical applications for temporary, written and recorded information such as newspapers, magazines, posters, notepads, easels, indications on daily life products, oxygen sensors and rewritable tags for multiple uses “, specifies the researcher.
The other advantage is monetary. » The coating materials are indeed inexpensive and the cost of production should be low since the coating material can be applied to the surface of conventional paper by simple processes such as dipping or spraying. “, continues Yadong Yin. It will nevertheless be necessary to wait to see such a method of printing becoming more democratic. » Our next step is to build a laser printer that uses this rewritable paper, to enable faster printing. We will also look for effective methods to be able to print in all colors concludes the researcher.