Cellulose-based paper is among the oldest mediums for script and is still ubiquitous today. In fact, the wide-spread use of paper is becoming an environmental burden: significant amounts of trees and water are consumed in its production and paper disposal results in paper and land pollution. Although a lot of paper is recycled, even this process generates an ink-sludge that harms the environment.
Even in time where personal electronic devices like smartphones are dampening the increase of paper consumption, a more environmentally alternative to paper is highly desirable.
Rewritable paper is attractive for addressing those issues, provided it is obtained by an environmentally conscious manufacturing process, uses an uncomplicated erasing method, and offers a long reusability lifetime. Currently, several different approaches are investigated: electrophoretic inks, electrowetting inks, cholesteric liquid crystals, reprintable coatings on paper, and responsive photonic crystals.
However, all the above approaches fall short in at least one of the following: they often require compelx manufacturing processes, they are often unable to store data for an extended amount of time or the liquids applied in the write/erase process are degrading the paper over time.
Prof. Qibing Pei from the University of California Los Angeles, and co-workers from the Harbin Institute of Technology, P.R. China, and Hainan University, P.R. China achieve a superior rewritable paper by combining the bistability of shape memory polymers with the precise control offered by electroactive polymers.
This unique approach combines the merits of both polymers with the color tuning property of photonic crystals, yielding reconfigurable, bistable multi-color photonic crystal nanocomposites. In consequence, drawbacks of current rewritable paper are overcome:
Fabrication requires only a single curing step
The film is stable in both erased an written form without requiring extra enerhy
A heat-triggered erasing process avoids abrasive chemicals and writing does not need ink by relying on the films inherent properties, ensuring stability for over 500 write-erase cycles.
A pixelated electrode matrix substitutes special stamps or inks
The developed an ink-free rewritable paper concept combining the state-of-the-art in photonic crystals, shape memory polymers, and electroactive polymers in a single nanocomposite. The resulting paper is a zero-energy, long term data storage medium that provides the additional advantage of easily controlled rewritability.
In the next step, the researchers seek to improve the polymer matrix toward targeting full-color range photonic paper. First author Yu Xie believes that the “interdisciplinary approach provides people with a perspective to look at a problem in a new light, and I hope our research on ink-free rewritable nanocomposites can stimulate other brilliant minds to pave the way for a true paper replacement.”
Qibing Pei admits that “playing with color is always joyful. In developing the rewritable paper, we have e-fashion in mind. Yu even considers designing her own fashionable dresses one day.”
To learn more about this fascinating approach to re-writable paper and other great science, please visit the Advanced Functional Materials homepage.