The Preparation of a Novel Silicone Optical Adhesive with Low Hardness and High Refractive Index

Hydroxyl-terminated polydiphenyl-methylphenyl siloxane (PDPMPS-OH) was synthesized by a non-hydrolysis sol–gel condensation method, using diphenylsilanediol (DPDS) and methylphenyl dimethoxysilane (MPDMS) as the raw materials. Subsequently, the synthesized PDPMPS-OH was reacted with divinyltetramethyldisiloxane (MM^vi) to produce a vinyl-terminated polydiphenyl-methylphenyl siloxane (PDPMPS-Vi) with a high refractive index of 1.580 and a long chain linear structure. The optical adhesive product (CSOA) cured by PDPMPS-Vi and a hydrogen-containing silicone resin, exhibits excellent optical performance, high reliability, and significantly enhanced tensile strength (up to 384 kPa), hardness (up to 48 O), and elongation at break (up to 237.9%), as well as a refractive index of up to 1.575. This adhesive demonstrates remarkable performance as an optical component adhesive.