Bistable and Reconfigurable Photonic Crystals-Electroactive Shape Memory Polymer Nanocomposite for Ink-Free Rewritable Paper

Paper has remained the world's most-widely accessible information medium even as sustainable and reusable paper replacements have attracted increasing attention. Here, an ink-free rewritable paper concept is developed that combines recent developments in photonic crystals, shape memory polymers, and electroactive polymers in a nanocomposite that matches the benefits of paper as a zero-energy, long-term data storage medium, but provides the additional advantage of rewritability. The rewritable paper consists of a ferroferric oxide-carbon (Fe3O4@C) core-shell nanoparticle (NP)-based photonic crystal embedded in a bistable electroactive polymer (BSEP). Electrical actuation induces large deformation in the z-axis of the nanocomposite, creating distinct color change in the actuated area. This nanocomposite stores high fidelity color images without inks, the images remain stable after more than a year of storage in ambient conditions, and the stored images can then be rewritten over 500 times without degrading. A seven-segment numerical display is also demonstrated.