Bis[3-(triethoxysilyl)propyl]tetrasulfide

Bis[3-(triethoxysilyl)propyl]tetrasulfide (CAS 40372-72-3) is a bifunctional organosilane coupling agent commercially known as Si 69, Silquest A-1289, B 2494, and Unisilan 41. It carries no assigned E-code. The molecule combines a silane group for mineral surface bonding with a polysulfide bridge for polymer integration.

In rubber and tire compounding, it chemically bonds silica fillers to diene rubber matrices by reacting its ethoxy groups with silanol sites on the filler surface while the tetrasulfide chain co-vulcanizes with the rubber network, improving reinforcement efficiency and reducing rolling resistance. It also serves as an adhesion promoter in silane-modified polymer sealants and coatings applied to glass or metal substrates.

This material is supplied as a liquid and is subject to REACH registration requirements within the European Economic Area. It is handled under HS code 29309090. Buyers should confirm grade specifications, purity certificates, and packaging formats directly with the supplier to meet their formulation requirements.