Smart materials for light absorptive rewritable paper: Chromic mechanisms and structural design

Rewritable paper (RP) which takes advantages of stimuli-responsive color-changing materials/smart materials and can be used multiple times has been demonstrated to hold potential to reduce human waste of paper and alleviate the increasingly severe environmental issues. To make the RP closer to the way that people are accustomed to reading and more practical for daily life, interest and effort toward smart materials with clearly visible or naked-eye color-switching properties are particularly important. In this review, depending upon the stimulation protocol, five types of stimuli (thermo-, water-related-, light-, stress-, and electric-field-) smart chromogenic materials and systems with visible color switching applied in light absorptive display for RP are focused on. In each section, different stimulus-chromic molecules and their corresponding systems are discussed to explore the design concepts, methodologies, working mechanisms, and pros and cons of various chromogenic materials used in light absorptive RP. In addition, the challenges and prospects are sketched to provide strategies to explore more smart materials for high-performance RP and its relative techniques.