Preparation of Photochromic Microcapsules of Poly(methyl methacrylate)/Inorganic Metal Oxide Composite Shells with UV‐Resistant Properties and Application to Printing on Cotton Fabrics

Abstract

AbstractTo further enhance the fatigue resistance of spiropyran‐based photochromic materials and to explore the functionality of organic–inorganic metal oxide microcapsule shell materials, cross‐linked (P(MMA‐PETA)) and homopolymer (PMMA) shells have been developed by cross‐linking TiO2 and hybridizing ZnO on a PMMA matrix. PMMA/TiO2 photochromic microcapsules and PMMA/ZnO photochromic microcapsules with ultraviolet (UV)‐absorbing function are prepared by successfully encapsulating spiropyran photochromic compounds using these two composite shells. The results show that both microcapsules exhibit a complete spherical core–shell structure with good UV resistance and thermal stability. The TG test underlines a 50% coating rate of PMMA/ZnO microcapsules on spiropyran photochromic material, with an optimal ZnO addition of 10% and particle size range from 2 to 8 µm, effectively blocking UV‐A and part UV‐B radiation. Further, a 75% maximal coating rate is observed for PMMA/TiO2 microcapsules on spiropyran with optimal TiO2 addition at 2–4%, a particle size of around 5 µm, diffusely reflecting 48% of UV rays. The photochromic fabrics prepared with PMMA/TiO2 microcapsules have better UV resistance, with a UV protection factor value of 59.48, and excellent fatigue resistance after at least 30 cycles of UV–visible light irradiation.