Application of surfactant
1. Cosmetics
Surfactants are widely used in various cosmetics as emulsifiers, penetrants, detergents, softeners, wetting agents, bactericides, dispersants, solubilizers, antistatic agents, hair dyes, etc. Non-ionic surfactants are the most commonly used in cosmetics because they are non-irritating and easily compatible with other components. They are generally fatty acid esters and polyethers.
2. Detergent
Surfactants have high-efficiency cleaning and disinfecting functions, and have already become the most important component of cleaning products. Surfactant is the main component of detergent, it has a series of physical and chemical effects (such as: wetting, penetrating, emulsifying, solubilizing, dispersing, foaming, etc.) between dirt and solid surface. Mechanical agitation for washing effect. The most widely used and most widely used are anionic and nonionic surfactants. Cationic and amphoteric surfactants are only used when producing certain special types and functions of detergents. The main varieties are LAS (referred to as alkyl alkyl sulfonate fat salt), AES (fatty alcohol polyoxyethylene ether sulfate), MES (α-sulfonic acid fatty acid fat salt), AOS (α-alkenyl sulfonate) Alkyl polyoxyethylene ether, alkyl phenol polyoxyethylene ether, fatty acyl diethanolamine, amino acid type, betaine type, etc.
3. Pharmaceutical field
Surfactants have the effects of wetting, emulsifying, solubilizing, etc., so they are widely used as excipients for pharmaceutical preparations, especially in the pharmaceutical microemulsion technology developed in recent years. In drug synthesis, surfactants can be used as phase transfer catalysts, which can change the degree of solvation of ions, thereby increasing the reactivity of ions, allowing the reaction to proceed in a heterogeneous system, the reaction efficiency is greatly improved Surfactants are often used as solubilizers and sensitizers in analysis, especially in drug fluorescence spectroscopy. In the pharmaceutical industry, pre-surgery skin disinfection, wound or mucous membrane disinfection, instrument disinfection and environmental disinfection, etc., because surfactants can strongly interact with bacterial biofilm proteins, denature or lose function, and act as bactericides and disinfectants being widely used.
The efficacy of surfactants
1. Wetting effect
When a solid contacts a liquid, the original solid / gas and liquid / gas interfaces disappear and a new solid / liquid interface is formed. This process is called wetting. For example, textile fiber is a porous substance with a huge surface. When the solution spreads along the fiber, it will enter the gap between the fibers and drive the air out, turning the original air / fiber interface into a liquid / fiber interface. It is a typical wetting process; while the solution will enter the fiber at the same time, this process is called infiltration. Surfactants that help wetting and penetration occur are called wetting agents and penetrants.
2. Emulsification
Emulsification refers to two liquids (such as oil and water) that are not in phase with each other. One of the liquids is evenly dispersed into another liquid with extremely small particles (particle size of 10-8 ~ 10-5m) The role of emulsion. Dispersing oil droplets into water is called oil-in-water emulsion (O / W), and water droplets dispersed into oil is called water-in-oil emulsion (W / O). The surfactant that can help emulsification is called emulsifier. The surfactant used as an emulsifier has two functions of stabilization and protection.
3. Decontamination effect
Due to the emulsifying effect of the surfactant, the grease dirt particles detached from the solid surface can be stably emulsified and dispersed in the aqueous solution, and no longer deposit on the washed surface to form recontamination.
4. Foaming effect
The state in which gas is dispersed in a liquid is called a bubble. If a liquid is easy to form a film and is not easy to break, this liquid will produce a lot of foam when stirred. After the foam is generated, the gas / liquid surface area in the system greatly increases, making the system unstable, so the foam is prone to burst. When the surfactant is added to the solution, the surfactant molecules are adsorbed at the gas / liquid interface, which not only reduces the surface tension between the gas / liquid phases, but also forms a single molecule film with a certain mechanical strength so that the foam is not easily broken.
Shaoxing Shangyu Simo Research institute of organic Chemistry
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