Innovative Synthesis of Photo-Responsive, Self-Healing Silicone Elastomers with Enhanced Mechanical Properties and Thermal Stability

Photo-responsive materials have garnered significant interest for their ability to react to non-contact stimuli, though achieving self-healing under gentle conditions remains an elusive goal. In this research, an innovative and straightforward approach for synthesizing silicone elastomers is proposed that not only self-heal at room temperature but also possess unique photochromic properties and adjustable mechanical strength, along with being both transparent and reprocessable. Initially, aldehyde-bifunctional dithiophene-ethylene molecules with dialdehyde groups (DTEM) and isocyanurate (IPDI) is introduced into the aminopropyl-terminated polydimethylsiloxane (H₂N-PDMS-NH₂) matrix. Subsequently, palladium is incorporated to enhance coordination within the matrix. These silicone elastomers transition to a blue state under 254 nm UV light and revert to transparency under 580 nm light. Remarkably, they demonstrate excellent thermal stability at temperatures up to 100 °C and show superior fatigue resistance. The optical switching capabilities of the silicone elastomers significantly affect both their mechanical characteristics and self-healing abilities. Notably, the PDMS-DTEM-IPDI-@Pd silicone elastomer, featuring closed-loop photo-switching molecules, exhibits a fracture toughness that is 1.3 times greater and a room temperature self-healing efficiency 1.4 times higher than its open-loop counterparts. This novel photo-responsive silicone elastomer offers promising potential for applications in data writing and erasure, UV protective coatings, and micro-trace development.