Chemical properties of poly propylene glycol 2000 peg

The properties vary according to the molecular weight, from colorless, odorless, viscous liquid to waxy solid. The molecular weight of PEG is between 200-600, and it is liquid at room temperature. The peg with molecular weight above 600 gradually becomes semi-solid. With the difference of average molecular weight, the properties are also different. From colorless and odorless viscous liquid to waxy solid. With the increase of molecular weight, its hygroscopic capacity decreased. Peg is soluble in water, ethanol and many other organic solvents. Low vapor pressure, stable for heat, acid and alkali. Peg does not work with many chemicals. It has good hygroscopicity, lubricity and cohesiveness. Non toxic, non irritating.

In general, peg is stable, but it can react with oxygen in air at 120 ℃ or higher. In an inert atmosphere (such as nitrogen and carbon dioxide), even when heated to 200-240 ℃, it will not change. When the temperature rises to 300 ℃, it will undergo thermal cracking. Adding antioxidant, such as phenothiazine with mass fraction of 0.25% ~ 0.5%, can improve its chemical stability. Any of its decomposition products are volatile and do not form hard shell or slimy deposits.

Polyethylene glycol is a kind of polymer of hydrolysis product of ethylene oxide, which is non-toxic and non irritant. It is widely used in various pharmaceutical preparations. The toxicity of PEG with low molecular weight is relatively high. In a word, the toxicity of PEG is relatively low. Local application of PEG, especially mucosal administration, can cause irritation pain. In the external lotion, the product can increase the flexibility of the skin, and has a moisturizing effect similar to that of glycerin. Diarrhea can occur in large doses. In the injection, the concentration of polyethylene glycol 300 is about 30% (V / V), and hemolysis may occur when the concentration is more than 40% (V / V).

The addition polymer of polyepoxyethane and water. When the molecular weight is below 700, it is colorless, odorless and non-volatile viscous liquid at 20 ℃, with slight water absorption. Those with molecular weight between 700 and 900 are semisolid. Those with molecular weight of 1000 or above are light white waxy solid or flocculent paraffin or flowing powder. It is miscible in water and many organic solvents, such as alcohol, ketone, chloroform, glyceride and aromatic hydrocarbon; it is insoluble in most aliphatic hydrocarbons and ether.

With the increase of molecular weight, the water solubility, vapor pressure, water absorption and organic solvent solubility of PEG decreased, while the freezing point, relative density, flash point and viscosity increased. It is heat stable, does not work with many chemicals and does not hydrolyze.