There are numerous types of silicone oil, including methyl silicone oil, hydrogen-containing silicone oil, hydroxyl silicone oil, amino silicone oil, etc. This article briefly introduces the structure, properties and research status of methyl silicone oil (PDMS) and hydrogen-containing silicone oil. 
1.Methyl silicone oil 
Polydimethylsiloxane (PDMS), also known as methyl silicone oil or dimethyl silicone oil, is a typical representative of organic silicone hydrophobic agents. Its hydrophobicity stems from the alternating arrangement of hydrophobic methyl groups and flexible silicon-oxygen main chains in the molecule. When PDMS modifies the fiber surface through impregnation or co-spinning processes, a hydrophobic layer with a low surface energy interface is formed on the fiber membrane surface to achieve hydrophobic function. Some researchers have successfully spun PA/PDMS nanofiber membranes by introducing PDMS in situ into the PA spinning solution through one-step electrospinning technology. The water pressure resistance of this membrane is 28.3 kPa, and the moisture permeability flux is 3.77 kg m-2 d-1, demonstrating excellent waterproof and moisture-permeable performance. 
2. Hydrogen-containing silicone oil 
Polydimethylhydrogensiloxane (PMHS), often referred to as hydrogen-containing silicone oil or hydrogen-containing silane, is a representative of functional organosilicon compounds. The highly reactive Si-H bonds in its molecular structure endow it with remarkable cross-linking properties. This compound typically appears as a slightly yellow or colorless transparent viscous liquid and features water insolubility, excellent thermal stability, and chemical inertness. 
Under specific reaction conditions, for instance, with Pt catalyst as the catalyst, PMHS can effectively serve as a crosslinking agent for addition-cured liquid silicone rubber, significantly enhancing the water resistance of the silicone rubber. By blending PMHS with PDMS and undergoing a series of chemical reactions including high-temperature heat treatment, hydrolysis, and condensation, the linear molecular chain structure is reconfigured into a cross-linked network structure, greatly improving the mechanical properties of the composite material. Moreover, a highly dense and highly water-resistant hydrophobic film can be formed on the fiber surface, endowing the material with excellent and long-lasting water repellency. This characteristic makes PMHS highly valuable in the waterproof treatment of textiles. After being treated with PMHS, textiles can maintain their original comfort and breathability while achieving significant water resistance. 
Some researchers introduced PMHS in situ into the PU spinning solution and prepared PU/PMHS nanofiber membranes through electrospinning. After thermal treatment, the water pressure resistance of the fiber membrane reached 54.1 kPa, and the moisture permeability rate was 9.5 kg m-2 d-1, demonstrating excellent waterproof and moisture-permeable properties.