Easily prepared superhydrophobic photochromic composite and its application in waterproof rewritable paper

Ink-free rewritable paper has attracted extensive social attention because of its potential advantages in recycling and sustainable utilization of resources. In this work, a double-coating rewritable paper composed of AMT/PVP and PDMS/SiO2 with superhydrophobicity, fast photoresponsivity, and excellent photochromic repeatability is developed. As an organic–inorganic hybrid photochromic material, the well conjugated system of rewritable paper greatly improves the coloring process. In ambient conditions, the sample can be colored in seconds under ultraviolet radiation and reaches saturation within 3 min, whose reflectance at 670 nm decreases to 3.53%. Despite the sample being treated of 15 coloring-erasing cycles, its color intensity has no significant change. More importantly, the sample surface possesses excellent superhydrophobic properties, endowing it with stability of photochromic properties when contacting water. Given the advantages of excellent photochromism, waterproof property, low cost and easy scale production, this superhydrophobic rewritable paper holds a promising prospect for convenient and practical usage.