Introduction and application of polyethylene glycol

Polyethylene glycol (PEG), also known as polyethylene glycol ether, CAS No. 25322-68-3, chemical structural formula HO (CH2CH2O) nH, is prepared by gradual addition reaction of ethylene oxide and water or ethylene glycol as raw materials, and its raw materials are mainly from petroleum products.

With the increase of polymerization degree, the physical appearance and properties of polyethylene glycol gradually change:

Those with a relative molecular weight of 200-600 are liquid at room temperature, and those with a relative molecular weight of more than 600 gradually become semi-solid. With the increase of molecular weight, it changes from colorless and odorless viscous liquid to waxy solid, and its hygroscopic capacity decreases accordingly. It has the chemical properties of alcohol and can react with fatty acids to form esters. Soluble in water, ethanol and various organic solvents. It is stable to heat, acid and alkali, and has no effect on many chemicals. It has good hygroscopicity, adhesion and lubricity. It is non-toxic and non-irritating. It is harmless to humans and animals.

Polyethylene glycol (PEG) has a strong water absorption ability. It can absorb water from the air under normal temperature conditions. The liquid can be mixed with water in any proportion. When the temperature rises, the solid polyethylene glycol of any fraction can be miscible with water in any proportion. When the temperature reaches the boiling point of water, the polymer will precipitate. The precipitation temperature depends on the molecular weight and concentration of the polymer. Polyethylene glycol (PEG) is a non-ionic polymer, which is stable under normal conditions. It can oxidize with oxygen in the air at 120 ℃ or higher. It is protected by inert gases such as carbon dioxide or nitrogen, and does not change at 200~240 ℃. When it rises to about 300 ℃, the molecular chain segment breaks and degrades.

[Performance and application]

1. Polyethylene glycol series products can be used for pharmaceuticals. Polyethylene glycol with low relative molecular weight can be used as solvent, cosolvent, o/w type emulsifier and stabilizer, used to make cement suspension, flocculant, emulsion, injection, etc., and also used as water-soluble ointment matrix and suppository matrix. Solid waxy polyethylene glycol with high relative molecular weight is often used to increase the viscosity and solidity of low molecular weight liquid PEG, as well as to compensate other drugs; For drugs that are not easily soluble in water, this product can be used as the carrier of solid dispersant to achieve the purpose of solid dispersion. PEG4000 and PEG6000 are good coating materials, hydrophilic polishing materials, film materials and capsule materials, plasticizers, lubricants and drop pills matrix, which are used to prepare tablets, pills, capsules, microcapsules, etc.

2. Polyethylene glycol series products can be used as raw materials for ester surfactants.

3. PEG-200 can be used as a medium for organic synthesis and a heat carrier with high requirements, and as a humectant, inorganic salt solubilizer and viscosity regulator in the daily chemical industry; Used as softener and antistatic agent in textile industry; It is used as a wetting agent in the paper and pesticide industries.

4. PEG-400, PEG-600 and PEG-800 are used as substrates for medicine and cosmetics, lubricants and wetting agents for rubber industry and textile industry. PEG-600 is added to the electrolyte in the metal industry to enhance the grinding effect and enhance the luster of the metal surface.

5. PEG-1000 and PEG-1500 are used as substrates or lubricants and softeners in the pharmaceutical, textile and cosmetics industries; Used as a dispersant in the paint industry to improve the water dispersibility and flexibility of the resin, with the dosage of 10~30%; In ink, it can improve the solubility of dyes and reduce their volatility. It is especially suitable for waxed paper and printing ink, and can also be used to adjust the viscosity of ink in ballpoint pen ink; It is used as a dispersant in rubber industry to promote vulcanization and as a dispersant for carbon black fillers.

6. PEG-2000 and PEG-3000 are used as casting agent for metal processing, lubricant and cutting fluid for metal wire drawing, stamping or forming, grinding, cooling, lubricating, polishing agent, welding agent, etc; It is used as a lubricant in the paper industry and also as a hot-melt adhesive to increase the rapid rewetting ability.

7. PEG-4000 and PEG-6000 are used as substrates in the production of medicine and cosmetics industries to regulate viscosity and melting point; Used as a finishing agent in the paper industry to increase the gloss and smoothness of the paper; As an additive in the rubber industry, it can increase the lubricity and plasticity of rubber products, reduce the power consumption in the processing process, and extend the service life of rubber products; Used as lubricant and coolant in metal processing industry, dispersant and emulsifier in pesticide and pigment industry production; It is used as antistatic agent and lubricant in textile industry.

8. PEG8000 is used as a matrix in the production of medicine and cosmetics industry, and plays a role in regulating viscosity and melting point; It is used as lubricant and coolant in rubber and metal processing industry, and as dispersant and emulsifier in pesticide and pigment industry; It is used as antistatic agent and lubricant in textile industry.