Polydimethylsiloxane

Polydimethylsiloxane is a polymer with a wide range of applications and excellent chemical and physical properties. The following is a detailed introduction about polydimethylsiloxane:

1. Chemical Structure and Naming

• chemical formula：(C₂H₆OSi)ₙ

• aliasDimethyl silicone oil

2. Physical and chemical properties

• appearanceDepending on the relative molecular weight, the appearance ranges from colorless and transparent volatile liquids to extremely high viscosity liquids or silicone gel.

• Taste and TransparencyOdorless and highly transparent.

• thermal stabilityIt has heat resistance and cold resistance, and can be used for a long time at -50 ℃ to 200 ℃.

• physical characteristicsViscosity changes little with temperature, waterproof, low surface tension, thermal conductivity (thermal conductivity coefficient of 0.134-0.159W/(m · K)), and light transmittance (light transmittance of 100%).

• chemical stabilityNon toxic and odorless, with physiological inertness, good chemical stability, electrical insulation and weather resistance, good hydrophobicity, and high shear resistance.

3. Application Fields

• Cosmetics：

• Applying low surface tension, easy spreading, and suitable viscosity gives personal care products a lubricating and greasy feeling, making the skin soft.

• Has anti foaming, defoaming, and anti foaming effects, preventing the phenomenon of "whitening" when applying the product.

• Different viscosities result in different application effects, and low viscosity gives the skin a dry and comfortable feeling.

• Electrical appliancesElectronic connectors that can be used in the electrical and electronic industry.

• Leather goodsUsed as a hydrophobic agent, softener, hand feel improver, defoamer in the dyeing industry, lubricant for sewing threads, etc.

• Brightening agentSuitable as a brightening agent ingredient for automobiles, furniture, shoes, cement products, etc.

• Release agentCan be used as a release agent for rubber or plastic products (brake pads, screws, plugs, etc.) and EVA shoe materials.

• lubricantCan be used as a lubricant for extruding rubber products such as conveyor belts, as well as lubricants for textile processes.

• otherIt is a food grade defoamer that can be used for defoaming in the brewing and fermentation time of medicine and food.

4. Security

• Polydimethylsiloxane is non-toxic and odorless, and does not cause physiological reactions in the human body, so it is also used as a medical defoamer.

5. Production process

• The production process of polydimethylsiloxane is generally divided into two main methods: direct method and indirect method. The direct method involves steps such as hydrolysis reaction between silane based raw materials and sodium hydroxide under alcohol catalysis; The indirect rule involves the steps of nickel hydride reduction reaction between silicones and sodium chloride catalyzed by trimethyl alumina.

6. Composite applications

• Polydimethylsiloxane can be mixed with surfactants such as lanolin, stearyl alcohol, cetyl alcohol, glycerol monostearate, Tween, Span, etc. as emulsion matrix.

• Adding film forming agents such as PVP, PVA, and cellulose derivatives to this product can enhance its protective properties.

7. Summary

Polydimethylsiloxane, as a high molecular weight polymer, plays an important role in various fields such as cosmetics, electrical appliances, leather, brighteners, release agents, lubricants, etc. due to its excellent physicochemical properties and wide range of applications. Meanwhile, its unique production process and composite applications also provide more possibilities for its application.