Organosilicon surfactants have the advantages of cheap and easily obtained raw materials, mild and easy to control technology, wide application and large demand. They have good field performance, rapid development and large market potential. They are high-value-added fine chemical products. Domestic scholars are struggling to catch up with the international level in the research of silicone surfactants. Among them, structural geminiization has achieved some cutting-edge research results. Although it has not yet reached the application stage, it has greatly improved the specialty of this type of surfactant. Degree of research. At the same time, more progress has been made in the research on the cleaning and greening of processes and products. 1. Interface properties of silicone surfactants Since the main chain of the silicone surfactant is a soft Si—O bond, which is neither hydrophilic nor oleophilic, it can be used in aqueous solutions and non-aqueous media to which ordinary hydrocarbon surfactants cannot be applied. On the other hand, silicone surfactants are arranged on the interface with methyl groups, which can reduce the surface tension to about 20mN/m, while ordinary hydrocarbon surfactants are arranged on the interface with methylene groups, which can only reduce the surface tension. To about 30mN/m. Among the silicone surfactants, the most commonly used is EO/PO modified silicone surfactants, whose performance is related to various factors such as the ratio of EO/PO, the degree of polymerization of surfactants and so on. EO is the hydrophilic part of the surfactant-modified group, and PO is the lipophilic part. When the ratio of EO/PO changes, the performance of the silicone surfactant changes. The study found that if the EO/PO ratio becomes larger, the HLB value of the surfactant will increase, indicating that the hydrophilicity is enhanced; if the EO/PO ratio becomes smaller, the hydrophilicity of the surfactant will be weakened. When the length of EO of the grafted polyether modified silicone oil is the same, its surface tension increases as the degree of polymerization of polysiloxane decreases. This is because the shorter the molecular chain of polysiloxane, the tighter the accumulation at the air/water interface and the more methyl groups on the surface. When PO is introduced, the hydrophobicity of the polyether chain is increased, thereby increasing the surface tension of the polyether-modified silicone oil. 2. Super wettability of silicone surfactant Trisiloxane surfactants can not only reduce the interfacial tension of the oil/water interface, but may also wet and expand on low-energy hydrophobic surfaces. This ability is called "super-wetting" or "super-spreadability". This phenomenon is considered to be the presence of special surfactant aggregates in the solution. The reason why polydimethylsiloxane chains are easy to spread on polar surfaces (such as water, metals, fibers, etc.) is that the oxygen in the silicone chain can form oxygen bonds with polar molecules or atomic groups, which increases the silicone chain and polar The force between the molecules on the surface of the surface makes it spread into a monolayer, so that the hydrophobic siloxane lies on the polar surface into a unique "stretched chain" configuration, while the hydrophobicity of ordinary surfactants The base is upright on a polar surface. When the methyl group in the polysiloxane is replaced by other groups (such as large alkyl groups, alicyclic groups, aryl groups, silicon functional groups or carbon functional groups), it is bound to be inevitably due to changing the polarity or steric hindrance of the substituents Will affect the hydrophobicity of polysiloxane and the spreading speed and state on the polar surface. The number and distribution of substituents on the silicone chain will also have the same effect. For example, when a methyl group is replaced by a larger alkyl or aryl group, it will significantly reduce the spreading ability of the polysiloxane, while reducing its ability to orient on a polar surface. 3. The ability of silicone surfactant to stabilize emulsion Some grafted silicone surfactants can keep the emulsion in the presence of salt, ethanol, and organic solvents. This ability is not available in traditional hydrocarbon surfactants. Atomic microscopy (AFM) examination revealed that the silicon surfactant has an interaction force at the interface. Non-ionic surfactants will lose surface activity in 25% ethanol solution, while silicone surfactants can still reduce surface tension when the ethanol volume fraction reaches 80%. This property of silicone surfactants reflects that polydimethylsiloxane is not only hydrophobic, but as the content of polydimethylsiloxane increases, the silicone surfactant is also insoluble in organic solvents. 4. The role of silicone surfactants and CO2 Rocha et al. believe that polyoxyethylene ether trisiloxane surfactant can make CO2 and water form an emulsion. By adjusting the EO number and changing the "hydrophilic CO2 balance (HCB) value" of the surfactant, the emulsion can be coated with CO2 Water (W/C) is converted into CO2 (C/W). Sarbu et al. believe that the special properties of polysiloxane surfactant make it used in supercritical CO2. Fink et al. believed that the phase behavior of silicone surfactants in supercritical CO2 found that the phase behavior was very sensitive to CO2 phobic groups, but less sensitive to the size of siloxane, and found an irregular liquid crystal phase. Folk et al. prepared a series of cationic silicone surfactants and studied their behavior in high-density CO2. Changing the chain length and counter ion of polydimethylsiloxane will strongly change its surface activity in critical CO2. Silway specializes in modified silicone and formulation technology, and the product line covers agricultural silicone additives, silicone waterproofing agents, Innovative Silicone , sealants and additives, modified silicone for die casting, etc. Welcome to consult and order: https://www.silways.com/