Single-end trimethoxysilane-terminated silicone oil is a type of modified polydimethylsiloxane with a trimethoxysilyl group (-Si(OCH₃)₃) at one end of the molecular chain and an inert methyl group at the other. As a functional organosilicon intermediate, its core advantage lies in the synergy between the high reactivity of the terminal group and the excellent properties of the polysiloxane main chain. It has both directional reaction ability and weather resistance, hydrophobicity, and is a key raw material for high-end material modification and interface modification. Different from double-end or multi-end terminated products, it is more suitable for harsh scenarios of precise grafting and single interface modification.
From a molecular structure perspective, the trimethoxysilane terminal group is its core functional unit. It can generate reactive silanol groups (-Si-OH) after hydrolysis, which can undergo condensation reactions with hydroxyl, amino and other groups on the substrate surface to achieve directional anchoring, improving the adhesion and compatibility between materials. The polysiloxane main chain endows it with good flexibility, high and low temperature resistance (-50℃ to 200℃), electrical insulation and hydrophobicity. The combination of the two makes the product not only have adjustable reactivity, but also retain the inherent advantages of organosilicon. Its molecular weight can be adjusted between 1000-15000 through processes, and the viscosity is suitable for different construction and modification needs. The product purity and reactivity directly determine the downstream application effect.
The current mainstream preparation processes are mainly nucleophilic substitution and ring-opening copolymerization, which focus on the terminal reaction between trimethoxysilane terminating agent and polydimethylsiloxane prepolymer under the action of a catalyst, and the finished product is obtained through hydrolysis control, neutralization and purification, and removal of low-boiling substances. The traditional process has two pain points: first, poor terminal selectivity, which is prone to produce double-end terminated or uncapped by-products, resulting in insufficient product purity; second, the hydrolysis reaction is difficult to control, which is prone to cause excessive condensation of trimethoxysilane groups, affecting product reactivity and storage stability.
Process upgrades focus on precise control and green optimization: by optimizing the monomer ratio and reaction temperature, and adopting the method of stepwise addition of terminating agent, the terminal selectivity is improved, the single-end termination efficiency is increased to more than 97%, and the content of by-products is reduced; organotin and amine composite catalysts are used to replace traditional single catalysts, which can precisely control the hydrolysis reaction rate, avoid excessive condensation, and improve the uniformity of product performance. At the same time, solvent-free production processes are promoted to reduce volatile organic compound emissions, and the low-boiling substance removal process is optimized to reduce product volatile components, meeting the requirements of green chemical industry, and promoting the upgrading of products from general-purpose to high-end customized type to meet the needs of fine modification scenarios.