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25322-68-3
futurechem
25322-68-3
Poly(ethylene glycol), also known as polyethylene glycol, polyoxyethylene, PEG, PEO, POE, or macrogol, is a polyether polymer obtained by ring-opening polymerization of ethylene oxide. Its general chemical formula is H−(O−CH2−CH2)n−OH, CAS number 25322-68-3, and E number E1521. It is a series of products with molecular weights ranging from hundreds to millions: low molecular weight products are colorless, viscous liquids, while high molecular weight products are white, waxy solids. It is soluble in water, methanol, ethanol, acetonitrile, benzene, and dichloromethane, but insoluble in diethyl ether and hexane. Its aqueous solutions are neutral and hygroscopic. With its excellent water solubility, adjustable molecular weight, terminal hydroxyl reactivity, flexible chain lubrication, bioinertness, and low toxicity, polyethylene glycol is used in various fields, including industry , food, daily chemicals, and scientific research. In industry, it is used as a surfactant and raw material for polyurethane polyols, in metalworking fluids, plastic and rubber additives, ceramic binders, battery electrolytes, and cultural relic protection materials . In food and daily chemicals, it is used as an antifoaming agent and a raw material for skin care products, toothpaste, and other daily chemical products.
Basic identification information : Chemical formula C2nH4n+2On+1 (structural formula H−(O−CH2−CH2)n−OH); CAS No. 25322-68-3; EINECS 500-038-2; UNII 3WJQ0SDW1A; ECHA 100.105.546; ChEMBL 1201478; E No. E1521; Aliases: polyethylene glycol, polyoxyethylene, polyethylene oxide, PEG, PEO, POE, macrogol, Carbowax, etc.
Structurally , polyethylene glycol is composed of repeating ethylene oxide units (−O−CH2−CH2−) linked by ether bonds, with a hydroxyl group at each end; the molecular chain has a flexible helical conformation, and the oxygen in the ether bonds can form hydrogen bonds with water.
Physically , polyethylene glycol (PEG) is a colorless to white liquid, paste, or waxy solid. Its state transitions from liquid to solid as its molecular weight increases: PEG 200-600 is a viscous liquid, PEG 1000-2000 is a paste, and PEG 4000 and above are waxy solids. Its melting point increases with molecular weight (PEG 4000 approximately 50-58℃, PEG 6000 approximately 55-63℃). Its density is approximately 1.125 g/cm³. It is soluble in water, methanol, ethanol, acetonitrile, benzene, and dichloromethane, but insoluble in diethyl ether and hexane. It is hygroscopic. Its flash point is 182-287℃. It has good thermal stability, but prolonged exposure to high temperatures or contact with oxidants may lead to oxidative degradation.
Chemically , polyethylene glycol is a hydroxyl-terminated polyether: its two primary hydroxyl groups can undergo esterification, etherification, and urethane esterification reactions. It reacts with isocyanates to form polyurethane, esterifies with fatty acids to form PEG ester surfactants, and continues chain extension with ethylene oxide, etc. It can also be activated (such as methanesulfonation and aldehyde conversion) to couple with proteins and other biomacromolecules to achieve polyethylene glycolation. The ether bond is chemically stable, resistant to acids and alkalis (the ether bond can break under long-term action of strong acids and alkalis), and has moderate oxidation resistance. The molecular chain has good flexibility and can be used as a plasticizer and lubricant. The terminal hydroxyl groups endow it with reactivity, making it the parent material for the synthesis of many derivatives.
Why does polyethylene glycol play these roles in various fields such as industry, food, daily chemicals, and scientific research? Its mechanism of action mainly includes the following:
Hydrophilic and water-soluble mechanism : The ether oxygen (−O−) in the main chain of polyethylene glycol can form hydrogen bonds with water molecules, making it a water-soluble polymer. The larger the molecular weight, the greater the change in water solubility window and hygroscopicity. This is the basis for its use as a water-soluble lubricant, an additive in water-based systems, and a hydrophilic segment.
The mechanism of adjustable molecular weight : The degree of polymerization determines the chain length, which in turn determines the physical state (liquid, paste, wax), viscosity, melting point and water solubility. Different molecular weights correspond to different application windows, allowing the appropriate specifications to be selected according to the application. This is the premise for its serialized application.
Hydroxyl-terminated reactive mechanism : The primary hydroxyl groups at both ends can react with fatty acids, fatty alcohols, alkylphenols, isocyanates and activating reagents to attach polyethylene glycol segments to the structures of esters, ethers, polyurethanes and biomacromolecules, forming surfactants, polyether polyols and other derivatives. This is the chemical basis for its use as a synthetic parent.
Flexible chain lubrication film formation mechanism : Polyethylene glycol molecular chains are flexible and can be adsorbed and spread to form films on the surfaces of metals, fibers, paper and other materials, reducing the coefficient of friction and providing boundary lubrication. This is the basis for its use as a metalworking fluid, textile and papermaking auxiliary agent and release agent.
Plasticizing mechanism : Polyethylene glycol with a suitable molecular weight can penetrate into the polymer chains, weakening the inter-chain forces, increasing the chain segment mobility, and reducing the hardness and brittleness of the plastic. This is the basis for its use as a plasticizer for plastics such as PVC.
Amphiphilic coupling mechanism : The polyethylene glycol segments are hydrophilic ends, which, after coupling with hydrophobic groups, form an amphiphilic structure. They can be oriented at the oil-water interface, reduce interfacial tension, and achieve emulsification, dispersion and solubilization. This is the basis for its use as a hydrophilic head group of surfactants.
Electrolyte complexation mechanism : The ether bond oxygen on the polyoxyethylene chain segment can coordinate and complex with metal cations such as lithium ions to form ion transport channels, making polyoxyethylene an ion conductor. This is the basis for its use as a solid polymer electrolyte.
Bioinertness and low toxicity mechanism : Polyethylene glycol is chemically stable and not easily metabolized or degraded by organisms. Its single oral toxicity is very low, making it safe for use in food additives and daily chemical raw materials in human contact scenarios.
Corresponding products: fatty alcohol polyoxyethylene ether (AEO), alkylphenol polyoxyethylene ether (OP-10), Tween (polysorbate), Span, narrow distribution ethoxylates, polyether nonionic surfactants ( laundry detergent, dishwashing liquid, shampoo, etc. ) , pesticide emulsifiers, emulsion polymerization emulsifiers, etc.
Why it can be used for this purpose: Polyethylene glycol segments are the hydrophilic parts of surfactant molecules. Through ethoxylation, they couple with hydrophobic groups such as fatty alcohols, alkylphenols, and fatty acids to form an amphiphilic structure. They are oriented at the oil-water interface, reducing interfacial tension and achieving emulsification, dispersion, and solubilization. It is the core raw material for manufacturing nonionic surfactants.
Corresponding products: polyether polyols, spandex elastic fibers, polyurethane flexible foam, polyurethane rigid foam, polyurethane elastomers, PU synthetic leather, polyurethane coating resins, etc.
Why it can be used for this purpose: The terminal hydroxyl groups of polyethylene glycol react with isocyanate to produce polyurethane. Its flexible polyether segments, as soft segments, give polyurethane elasticity and flexibility. It is a key component of polyether polyols in spandex elastic fibers, foam plastics and elastomer formulations.
Corresponding products: water-soluble cutting fluid, grinding fluid, wire drawing fluid, rolling fluid, quenching media, metal cleaning agents, water-soluble rust inhibitors and lubricants, etc.
Why it can be used in this application: Polyethylene glycol has good water solubility and flexible molecular chains, which can be adsorbed on metal surfaces to form films, reducing friction and wear. At the same time, it is easily soluble in water and easy to clean, and has cooling, lubrication and cleaning functions. It is an important component of water-based metalworking fluids and industrial lubricants.
Corresponding products: PVC plasticizers, plastic release agents, internal lubricants, antistatic agents, rubber processing aids, color masterbatch carriers, etc.
Why it can be used for this purpose: Polyethylene glycol with a suitable molecular weight can penetrate into the polymer chains to weaken the inter-chain forces, reduce the hardness and brittleness of plastics, and play a plasticizing role; its flexible chains form a film at the interface between the mold and the product, which facilitates demolding, and has internal lubrication and antistatic functions, making it a general-purpose additive for plastic and rubber processing.
Corresponding products: inkjet ink solvents, printhead lubricants, water-based coating leveling agents, ink dispersants, paint fillers, paper coating agents, etc.
Why it can be used for this purpose: Polyethylene glycol has good solubility and compatibility with dyes and pigments. It can adjust the viscosity and jetting performance of ink and lubricate the printhead. In water-based coatings, it acts as a leveling and dispersing agent to improve the uniformity of the coating film. It is a commonly used additive in the formulation of coatings, inks and printing consumables.
Corresponding products: softeners, antistatic agents, leveling agents, penetrants, warp sizing agents, chemical fiber oils, etc.
Why it can be used in this way: Polyethylene glycol adsorbs onto the fiber surface to form a hydrophilic lubricating film, giving the fabric a soft feel and reducing static electricity accumulation. Its derivatives improve leveling and penetration in the dye bath and are commonly used auxiliary components in textile printing and dyeing processes.
Corresponding products: coating lubricants, paper softeners, calendering aids, anti-blocking agents, wet end additives, etc.
Why it can be used for this purpose: Polyethylene glycol acts as a lubricant in paper coating formulations, which can reduce friction between the doctor blade and the coating, improve the gloss and smoothness of the coating, and give the paper softness and non-stick properties. It is a commonly used additive in paper coating and paper processing.
Corresponding products: technical ceramic binders, alumina/silicon carbide molding binders, ceramic granulation agents, powder metallurgy binders, electronic ceramic additives, etc.
Why it can be used for this purpose: Polyethylene glycol aqueous solution has adhesive properties and can be used as a molding binder for ceramic powder and metal powder. It allows the powder to maintain the strength of the green body before pressing and sintering, and completely burns off the ash during the sintering process, leaving no ash. It is a commonly used organic binder for technical ceramics and powder metallurgy molding.
Corresponding products: solid polymer electrolytes (PEO-based), lithium battery polymer electrolytes, photoelectrochemical battery electrolytes, heat transfer fluids for electronic devices, gas chromatography stationary phases, electronic-grade solvents, etc.
Why can it be used in this way? The ether bonds on the polyethylene oxide segments can coordinate and complex with lithium ions to form ion conduction channels, making it a matrix for the research and application of solid polymer electrolytes. Polyethylene glycol can also be used as a heat transfer fluid in electronic testing equipment and a polar stationary phase in gas chromatography, making it a multifunctional material in the fields of electronics and analytical chemistry.
Corresponding products: green reaction solvents, Selexol gas desulfurization and decarbonization solvents, mass spectrometry calibration internal standards, organic synthesis media, phase transfer aids, etc.
Why it can be used in this application: Polyethylene glycol is thermally stable, has low volatility, and strong solubility for a variety of organic substances, making it a green reaction medium that can replace traditional solvents; its dimethyl ether derivatives have selective absorption capabilities for carbon dioxide and hydrogen sulfide, and can be used for the purification of syngas from coal gasification; its characteristic pyrolysis spectrum also makes it an internal standard for mass spectrometer calibration.
Corresponding products: soil wetting agents, pesticide formulation adjuvants, water-dispersible granule adjuvants, fertilizer additives, seed treatment agents, etc.
Why it can be used for this purpose: Polyethylene glycol can reduce the surface tension of aqueous solutions, improve the wetting and spreading of pesticide solutions on crop and soil surfaces, increase the effective utilization rate of pesticides and fertilizers, and improve the stability of formulations. It is a common water-soluble polymer adjuvant in agrochemical formulations.
Corresponding products: skin cream base, moisturizing lotion, toothpaste dispersant, personal lubricant, thickener for washing and care products, sunscreen formulation additives, etc.
Why it can be used in this way: Polyethylene glycol has good water solubility, moisture absorption and moisturizing properties, a gentle feel on the skin, and compatibility with a variety of ingredients. It can be used as a moisturizing base in skin care products, help dispersants to disperse evenly in toothpaste, and provide water-soluble lubrication in personal lubricant products. It is a commonly used multifunctional raw material in daily chemical formulations.
Corresponding products: food antifoaming agent (E1521), beverage defoaming components, food processing aids, etc.
Why it can be used for this purpose: Polyethylene glycol has low surface tension and can spread and destroy foam film quickly. As an antifoaming agent in food and beverages, it inhibits foaming during processing and filling. Its safety meets the standards for use as a food additive and is approved for use in food as a defoaming and processing aid.
Corresponding products: water-immersed wood preservative, archaeological artifact reinforcement agent, green wood stabilizer, desalination aid for wooden artifacts, etc.
Why it can be used for this purpose: Polyethylene glycol can penetrate into the interior of cultural relics such as wood to replace moisture. After drying, it maintains dimensional stability and prevents cracking and deformation. It is used for the protection and restoration of shipwrecks and water-damaged wooden cultural relics, as well as for the stabilization of raw materials. It is a classic material in the field of cultural relic protection.
Polyethylene glycol (CAS 25322-68-3) is a polyether polymer formed by the ring-opening polymerization of ethylene oxide. Its core properties include water solubility, adjustable molecular weight, reactive terminal hydroxyl groups, flexible chain lubrication, bioinertness, and low toxicity. It is used across various industries, including industry, food, daily chemicals, and scientific research. In industry, it is a surfactant and polyurethane polyol raw material, a metalworking fluid, a plastic and rubber additive, a ceramic binder, a battery electrolyte, a reaction medium, and a material for cultural relic preservation. In daily chemicals, it is used as a raw material in skincare products, toothpaste, and other personal care products. In food, it is an antifoaming agent (E1521). Understanding its polyether structure and the reactivity of its terminal hydroxyl groups explains why it can function as a hydrophilic segment of nonionic surfactants, a soft segment of polyurethane polyols, and also provide lubrication, plasticizing, bonding, ion conduction, and facilitating the preservation of cultural relics—this is precisely why it is used across surfactant, polyurethane, metal processing, plastics, paints and inks, textiles, papermaking, ceramics, batteries, chemicals, agriculture, daily chemicals, food, and cultural relic preservation.
