Polyethylene glycol, alias oxidized polyethylene, is a high molecular polymer, its chemical structure is HO(CH2CH2O)nH, n is an integer greater than 4, therefore, the relative molecular weight of polyethylene glycol varies from 200-7000 , In daily use, in order to distinguish, a number is usually added after the name, for example, polyethylene glycol-300 means polyethylene glycol with a molecular weight of 300. Polyethylene glycol has good water solubility, good compatibility with many organic substances, non-irritating and slightly bitter. Polyethylene glycol has good hygroscopicity, lubricity and adhesion, but its chemical properties vary with molecular weight. The above will gradually become a waxy solid, and at the same time, the hygroscopic ability, water solubility and vapor pressure will gradually become weaker with the increase of molecular weight. Polyethylene glycol has strong thermal stability, does not undergo hydrolysis, and basically does not react with other substances.
Polyethylene glycol has strong water solubility, is not volatile, mild and non-irritating, and has lubricity and physiological inertness, so it can make the skin moist, soft and happy after use, so it is often used in the cosmetics industry. . Polyethylene glycol with a molecular weight of less than 2000 is generally used in toothpaste, lotion, shaving cream, etc., and plays the role of wetting and viscosity adjustment. High molecular weight is often used in soaps, lipsticks, foundations and beauty cosmetics.
The lubricity of polyethylene glycol also makes it widely used in pharmaceutical preparations, topical preparations, injections, ophthalmic preparations, oral and rectal preparations. Polyethylene glycols in solid form and liquid polyethylene glycols can be mixed to make topical ointments of varying viscosities. These mixtures are also often used as suppository bases, to improve the stability of emulsions, and as film coatings.
Polyethylene glycol has such a wide range of uses, and there are many scientific researches based on it. Generally, you can prepare them yourself in the laboratory. Here is a synthetic method:
1. Add 120# gasoline to the reaction kettle, and add aluminum isopropoxide as a catalyst under stirring (control the amount of catalyst to be about 1.01-1.03% of the total monomer).
2. After replacing the air in the kettle with nitrogen, add the monomer ethylene oxide according to the mass ratio of solvent and ethylene oxide of 2:1. React at 10-20 degrees Celsius for 4 hours. Then the temperature was gradually raised to 35-40 degrees Celsius, and the reaction was continued for 3 hours.
3. After the polymerization reaction is over, the material is transferred to the still, the solvent is evaporated, the remaining material is cooled and crystallized and filtered to obtain a crude product. Polyvinyl alcohol is obtained after vacuum drying.
Storage and transportation conditions
Polyethylene glycol is chemically stable in air and solution, but easily hygroscopic with molecular weight below 2000. Not suitable for microbial growth, nor easy to rancid.
Polyethylene glycol and its aqueous solutions can be sterilized by autoclaving, filter sterilization, or gamma ray sterilization. If the solid state is sterilized by dry heat at 150°C for 1 hour, it can induce oxidation and degrade.
It should be stored in a cool, dry place in an airtight container. Liquid grade polyethylene glycol can be stored in stainless steel, aluminum, or glass containers.