Self-Healing Photochromic Elastomer Composites for Wearable UV-Sensors (Adv. Funct. Mater. 20/2023)

Photochromic materials have recently received strong interest for the development of wearable ultraviolet (UV) detection technologies because they do not require electronic components, resulting in systems and devices that change color upon irradiation. However, their implementation in wearable technology has lightweight, compliance, and durability (especially under mechanical stress) requirements that are limited by the materials’ properties. Here, a self-healing photochromic elastomer composite (photoPUSH) consisting of phosphomolybdic acid (PMA) in a self-healing polyurethane dynamic network with reversible disulfide bonds (PUSH) is presented. The unique properties of the dynamic polymer matrix enable multiple complementary functions in the UV-sensing composite: i) photochromism via electron donor groups without requiring additional dopants, ii) stretchability and durability via elastomeric properties, iii) healing of extreme mechanical damage via dynamic bonds, and iv) multimaterial integration via adhesive properties. PhotoPUSH composites exhibit excellent durability, tunable sensing range, and no loss of performance under mechanical stress and severe damage, as well as in underwater environments (waterproof). Leveraging these properties, soft, portable, multimaterial photoPUSH-based UV-sensing devices are developed for applications in environmental monitoring, packaging, and healthcare wearable technology (including skin-mounted, textile-mounted, and wristband devices) in challenging environments and tunable to different skin types.