The core difference between straight-chain vinyl silicone oil and side-chain vinyl silicone oil lies in the location distribution of vinyl groups. This difference directly affects their molecular structure, physical properties and application scenarios, as follows：


1. Molecular structure differences
Straight-chain vinyl silicone oil: The vinyl group is only located at both ends (end groups) of the molecular chain, and the molecular backbone is a straight-chain structure with no overhanging segments.Its molecular structural formula is：
CH₂=CH-Si(CH₃)₂O[(CH₃)₂SiO]ₙ(CH₃)₂Si-CH=CH₂
This structure gives it high molecular regularity, the viscosity range is usually 500-80000 MPa·s, and the vinyl content is 0.2%-1%.
Side chain vinyl silicone oil: Vinyl groups are distributed in the side chain positions of the molecular chain and may be located anywhere in the main chain (including the middle and both ends).The introduction of side chains increases the complexity of the molecular chain, resulting in a wider viscosity range (such as 50-1000 MPa·s), and the vinyl content can be adjusted by the number of side chains (preferably 0.1-1 mmol/g).
2. Comparison of physical properties
Crosslinking density and mechanical properties：
Due to the higher content of side-chain vinyl silicone oils, side-chain vinyl silicone oils form a denser crosslinking network after crosslinking and curing, with higher tensile strength, but lower elongation at break (the crosslinking point binds the molecular chain mobility).
Straight-chain vinyl silicone oil has lower crosslinking density, better elasticity, and higher elongation at break, which is suitable for scenarios where flexibility is required.
Fluidity and processability：
Straight-chain vinyl silicone oil has regular molecules, excellent fluidity when the viscosity is low, easy to mix evenly, and suitable for injection thermoforming process.
The viscosity of the side chain vinyl silicone oil can be adjusted in a wide range, but the fluidity of high-viscosity products is poor, and it needs to be selected according to the process requirements.
3. Application scenario differentiation
Straight chain vinyl silicone oil：
Silicone rubber production: As the basic rubber for adding liquid silicone rubber, it enhances strength and hardness.
Electronic potting: The low-viscosity end vinyl silicone oil ensures the fluidity of the potting glue while maintaining the mechanical properties.
Medical field: Good biocompatibility, used in the manufacture of flexible devices such as medical catheters and implants.
Side chain vinyl silicone oil：
High-performance silicone rubber: The high vinyl content of the side chain improves the crosslinking density, which is suitable for scenarios with high temperature resistance and high strength requirements (such as aerospace seals).
Electronic packaging: High crosslinking density provides excellent weather resistance and UV resistance, and extends the life of electronic components.
Special coatings: react with organic materials such as polyurethane and acrylic acid to prepare functional coatings that are resistant to aging and ultraviolet rays.