Smart pH indicating functional fabric based on reversible acidichromic self-colored microparticles

Our study focuses on developing a novel wearable fabric with reversible acidichromic properties by dyeing it with self-colored hollow microparticles as polymeric dyes. To synthesize the pH-responsive chromophore, we introduced a self-synthesized 3-methyl-3-2,2′-dihydroxydiethylamine azobenzene (MDPD) to polyurethane microparticle shells. This prevented any dye leakage compared to conventional dye microcapsules. The self-colored microparticles exhibited an approximately spherical shape, with the particle size distribution ranging from 400 nm to 900 nm, peaking around 600 nm. By covalently bonding MDPD to the molecular chain of the polyurethane shell, we increased thermal stability and avoided dye leakage. We calculated the actual content of MDPD in the shell to be 3.84 %. To investigate the pH-responsive chromic mechanism of self-colored hollow microparticles, we characterized their color properties at various pH values. The polyester fabric dyed with pH-responsive self-colored microparticles showed a K/S value of up to 4.8. The dyed fabric exhibited a clear color change from yellow to rose red after decreasing the pH value, with a highly reversible mode, excellent color fastness, and aging resistance. Furthermore, we analyzed the combination mechanism of microparticles and polyester fabrics, highlighting the reversibility and large-area flexibility of pH-responsive microparticle dyed fabrics. The ability to accurately monitor pH levels in real-time using these fabrics opens new avenues for creating intelligent and responsive textile-based devices. As we continue our research and development, we aim to explore and maximize the potential of these fabrics, making them a valuable and innovative addition to the realm of wearable technologies.