The surface activity and hydrophobic and oleophobic properties of fluorosilicone oil are derived from the synergistic effect of trifluoropropyl (-CF₃ group) and siloxane main chain (Si-O-Si) in its molecular structure. The specific mechanism and performance are as follows:

1. Surface activity mechanism and characteristics
‌Low surface tension‌
The surface tension of fluorosilicone oil can be reduced to ‌17–22 mN/m‌ (much lower than 72 mN/m of water). The -CF₃ groups in its structure are arranged in a directional manner at the interface to form a low-energy surface, which significantly enhances the wetting and spreading ability.

‌Application‌: When used as a defoamer, only 1ppm concentration is required to quickly penetrate the foam liquid film and destroy the surface tension balance.
‌Critical micelle concentration (CMC) advantage‌
Fluorosilicone surfactants (such as modified products containing polyether chains) can reach CMC values at low concentrations (0.13 g/L), reducing the surface tension of aqueous solutions to ‌22.8 mN/m‌ (about 21–24 mN/m for ordinary silicone oil).

2. Core principles of hydrophobicity and oleophobicity
‌Oriented molecular arrangement‌
Fluorosilicone oil forms an oriented molecular film with an outer layer of ‌-CF₃‌ on the surface of the substrate through adsorption. This structure has extremely low surface energy (about 20 mN/m), which significantly reduces the friction coefficient of the substrate.
‌Hydrophobic and oleophobic performance‌:
Contact angle to water ‌>110°‌ (about 95–105° for ordinary silicone oil;
Contact angle to oil solvents (such as crude oil, lubricating oil) ‌>80°‌, effectively blocking the penetration of oily media.
‌Chemical stability support‌
The synergistic effect of the high bond energy of the C-F bond (485 kJ/mol) and the Si-O-Si skeleton makes the hydrophobic and oleophobic film stable at high temperature (250°C), strong acid/alkali and organic solvents.

3. Performance comparison and application verification
‌Performance parameters‌ ‌Fluorosilicone oil‌ ‌Dimethyl silicone oil‌ ‌Perfluoropolyether‌ ‌Surface tension (mN/m)‌ 17–2215 21–245 16–2013
‌Water contact angle‌ >110°411 95–105°4 >110°13
‌Solvent resistance‌ Anti-swelling of acetone and benzene 35 Partial dissolution 5 Excellent solvent resistance13
‌Applicable temperature range‌ -60℃~250℃15 -50℃~200℃1 -70℃~300℃

4. Typical application scenarios
‌Surface treatment agent‌
Used for surface treatment of textiles and building materials (such as concrete), giving long-term water and oil resistance and reducing the adhesion of pollutants.
‌Precision instrument lubrication‌
Forming a lubricating film with a low friction coefficient (0.03–0.08) in micro-mechanical bearings and watch parts to avoid oil residue.
‌Special coating additives‌
Improve the anti-fouling property of coatings (such as ship anti-fouling coatings) and resist seawater erosion and biological attachment.

5. Performance limitations
‌High cost‌: Due to the complex synthesis of fluorinated monomers, the price is significantly higher than that of ordinary silicone oil;
‌Film formation dependence‌: The hydrophobic and oleophobic effect depends on the surface flatness of the substrate, and a rough surface may cause uneven distribution of the -CF₃ film.
In summary, fluorosilicone oil achieves ultra-low surface tension and stable hydrophobic and oleophobic properties through the molecular synergy of the -CF₃ group and the siloxane skeleton, and is irreplaceable in extreme environments and precision industries.