Optimized Sol–Gel Synthesis of Elastic Silicone Resins With Balanced Thermal Stability and Mechanical Properties

ABSTRACT Silicone rubber exhibits greater elasticity but poorer thermal stability than silicone resins, owing to its lower crosslinking density. Thus, this study introduces phenyltrimethoxysilane (PhTMS) into hydroxyl‐terminated polydimethylsiloxane (OH‐PDMS) through a sol–gel co‐hydrolysis and condensation approach, yielding elastic silicone resins (ESR) that combine the elasticity of silicone rubber with the thermal stability of silicone resins. The effects of PhTMS content and OH‐PDMS chain length on overall performance were systematically studied. The optimized ESR (5–300‐ESR‐v) showed a markedly higher T d5 (5% weight loss temperature) (389°C in air, 452°C in N 2 ) than OH‐PDMS‐v (350°C in air, 400°C in N 2 ), alongside superior mechanical performance and adhesive strength. Compared with traditional silicone resins, the resulting ESR are solvent‐free, low‐viscosity, and curable at room temperature, achieving an optimal balance of thermal stability, strength, and toughness. This makes them promising candidates for heat‐resistant materials.