Water as a Colorful Ink: Transparent, Rewritable Photonic Coatings Based on Colloidal Crystals Embedded in Chitosan Hydrogel
Although the current century is dominated by electronic device, paper is still believed to play a crucial role in information storage and distribution with the evidence of its tripled global consumption over the past decades. With more than 90% of all information in businesses printed on paper, most of which are disposed after only one-time reading and without de-ink. Not only would this be a huge wastage, but also bring disastrous impact to the environment such as pollution to air, water and land. Rewritable paper that can be reused for multiple times, therefore, is an attractive alternative supporting a perfect balance between economic development and environmental protection which would bring actual benefits to our society.
A research group led by WU Tianzhun at Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences developed a new rewritable paper with water as a colorful ink by using water as the trigger to tune the band-gap of photonic crystal coatings on solid substrates.They found that various colors could be achieved by adjusting the particle size of photonic coatings, or writing with aqueous solutions of certain pH. The photonic coatings can be erased and rewritten multiple times with no significant loss in color quality. Furthermore, the photonic coatings, which are transparent, enable fast and convenient visualization of the invisible photonic patterns with good tenability and reproducibility, offering potential applications for steganography, identification marking and anti-counterfeiting purposes.These results were published inJournal of Materials Chemistry C (2014, DOI: 10.1039/C5TC00217F. ).
This transparent and rewritable paper can serve as an environmentally friendly information storage devices to meet the sustainability of modern society.The work was supportedby the China Postdoctoral Science Foundation (Grant No. 2014M552252), National Natural Science Foundation of China (Grant Nos. 21404116, 51475451), Guangdong Innovative and Entrepreneurial Research Team Program (No. 2013S046) and Shenzhen Peacock Plan.
DU Xuemin, Ph.D.
Research Centre for Micro/Nano System & Bionic Medicine, Institute of Biomedical & Health Engineering, Shenzhen Institutes of Advanced Technology (SIAT), Chinese Academy of Sciences (CAS), Shenzhen 518035, China
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