Low-viscosity vinyl silicone oil is a linear polydimethylsiloxane with vinyl groups (CH₂=CH-) attached to the ends or side chains of its molecular backbone. Its key characteristic is that it exists as a readily flowable liquid at room temperature, with a viscosity significantly lower than conventional vinyl silicone oils. This low viscosity stems from its relatively low molecular weight and narrow molecular weight distribution. Its general molecular formula can be represented as (CH₂=CH)-(CH₃)₂SiO-[(CH₃)₂SiO]ₙ-Si(CH₃)₂-(CH=CH₂) or containing (CH₂=CH)(CH₃)SiO- units. The vinyl functional groups within its structure confer high chemical reactivity to this material, particularly enabling efficient hydrosilylation reactions with hydrogen-containing silicone oil in the presence of a platinum catalyst, forming a stable three-dimensional network structure. This reaction forms the basis for most of its applications.

In the preparation of High-Temperature Vulcanized silicone rubber (HTV), low-viscosity vinyl silicone oil serves as the raw gum prepolymer and is a key primary raw material. It plays a dual role here: on one hand, its low viscosity facilitates thorough and uniform mixing with fillers like silica and other additives (such as structure control agents) during the initial compounding stage, significantly improving processability and reducing energy consumption. On the other hand, it acts as a source of reactive vinyl groups. During the subsequent high-temperature vulcanization process, it undergoes an addition reaction with the crosslinker (hydrogen-containing silicone oil), building the elastomeric network of the silicone rubber. It is noteworthy that, leveraging its high reactivity, low-viscosity vinyl silicone oil can effectively replace traditional vinyl double-end-cappers for synthesizing vinyl-terminated polydimethylsiloxane raw gum. This method offers greater flexibility in molecular design, aiding in the production of raw gums with specific vinyl content and distribution, thereby allowing precise control over the final vulcanizate's physical and mechanical properties, such as hardness, tensile strength, and tear strength.

As an efficient modifier, low-viscosity vinyl silicone oil is widely used to enhance the properties of organic polymers such as polyurethane (PU) and acrylates. Its modification mechanisms primarily include physical blending modification and chemical copolymerization modification. In polyurethane systems, introducing polysiloxane segments through block or graft copolymerization leverages the high bond energy of the siloxane bond (Si-O, approximately 460 kJ/mol) and the oriented arrangement of methyl groups to significantly improve the material's weather resistance, UV resistance, heat oxidation resistance, and hydrolysis resistance. Simultaneously, the flexible siloxane backbone can effectively toughen the matrix, improving its low-temperature flexibility. In acrylic resins (e.g., for coatings, adhesives), incorporating a vinyl silicone oil component can reduce the surface energy of the resin, imparting excellent anti-adhesion and stain resistance to the product. Furthermore, through interpenetrating networks (IPN) or core-shell structures, it can enhance the toughness, impact resistance, and thermal stability of the acrylic resin, overcoming its inherent brittleness.

Moreover, low-viscosity vinyl silicone oil is the primary base polymer raw material for addition-cure Liquid Silicone Rubber (LSR) and silicone gels. In this field, its low viscosity is a critical processing parameter. It ensures that the mixing process of the base polymer with the catalyst and crosslinker is easy to perform, the system has good flowability, facilitates pouring or injection molding, and allows complete filling of fine structures in complex molds, while also aiding in the removal of air bubbles during production. Catalyzed by platinum catalysts, the addition reaction between vinyl and Si-H groups features a fixed stoichiometry, no by-products, low shrinkage, and controllable reaction depth. This enables the final LSR products to possess advantages such as good dimensional stability, high transparency, excellent biocompatibility, and tunable mechanical properties, making them widely used in high-end applications like electronic potting, medical tubing, infant care products, and new energy battery sealing. The soft, damping characteristics of silicone gels are also primarily achieved by adjusting the ratio and molecular structure of the base polymer (based on low-viscosity vinyl silicone oil) and the crosslinker.

In summary, leveraging its unique physical property of low viscosity and the highly reactive chemical nature of the vinyl group, low-viscosity vinyl silicone oil plays an indispensable and core role across multiple technological fields, ranging from silicone rubber synthesis to polymer material modification, and further to high-precision potting and molding. Its value is demonstrated in three aspects: optimizing processing techniques, serving as an active reactive component, and endowing final products with superior comprehensive properties.