Polyethylene glycol (PEG), also known as polyethylene oxide (PEO) or polyoxyethylene (POE), refers to an oligomer or polymer of ethylene oxide. These three names are generally used synonymously today, but historically polyethylene glycol has often referred to oligomers and polymers with a molecular weight below 20,000 g/mol, PEO to polymers with a molecular weight over molecular weight polymers.
PEO and POE can be liquid or low-melting solid depending on the molecular weight. Due to the influence of chain length, PEGs with different molecular weights often have different physical properties (such as viscosity) and different applications, but most PEGs have similar chemical properties. Low-molecular-weight polyethylene glycol usually refers to a relatively pure oligomer, which is more monodisperse; high-purity polyethylene glycol is crystalline, so X-rays can be used to determine its crystal structure. Due to the difficulty of purifying and isolating oligomeric polyethylene glycol, the price is usually 10-1000 times that of polydisperse polyethylene glycol. Those with a relative molecular mass between 700-900 are semi-solid. Those with a relative molecular weight of 1000 and above are pale white waxy solids or flakes of paraffin or fluid powder. Miscible in water, soluble in many organic solvents, such as alcohols, ketones, chloroform, glycerides and aromatic hydrocarbons. Its products combined with hydrophobic molecules can be used as nonionic surfactants. As the molecular weight increases, its water solubility, vapor pressure, water absorption, and solubility in organic solvents decrease accordingly, while the freezing point, relative density, flash point, and viscosity increase accordingly. Stable to heat, does not work with many chemicals, does not hydrolyze. The production method is obtained by polycondensation of ethylene glycol or polyaddition of ethylene oxide and water. Effects Polyethylene glycol can be used to modify drug proteins to protect drug molecules and prolong their half-life. Polyethylene glycol acts as a cell fusion agent. It causes the adhesion of adjacent cell membranes, which in turn allows cells to fuse into one cell. Polyethylene glycol is also used as an osmotic laxative. The powder with a molecular weight of 3350 is commonly used, and 17g is dissolved in water and taken orally every day to treat constipation.