Polyethylene Glycol PEG-2000 (Polyethylene Glycol 2000) is a high molecular weight compound obtained by the stepwise addition polymerization of ethylene oxide with water or ethylene glycol. Its molecular formula is H(OCH₂CH₂)nOH, with an average molecular weight of approximately 2000. It has active hydroxyl groups at the ends and is chemically stable. It can be used directly as a functional additive or as a synthetic intermediate to prepare various non-ionic surfactants through reactions such as esterification and etherification.
In terms of physical form, PEG-2000 is a white to slightly yellow waxy solid or flake at room temperature, with uniform color. Its melting point is about 50–55°C. When heated and melted, it becomes a transparent viscous liquid, and upon cooling, it returns to a solid state, exhibiting excellent thermal reversibility, which facilitates processing under different temperature conditions. The product has a flash point greater than 220°C (closed cup method), very low volatility, and does not volatilize or decompose under normal processing temperatures.
As a non-ionic polymer, PEG-2000 is well compatible with anionic, cationic, and other non-ionic substances. It is resistant to acids, alkalis, and hard water, maintaining stable performance over a wide pH range and water quality conditions. Its safety profile is outstanding; it is not classified as a hazardous chemical. The acute oral toxicity LD₅₀ is greater than 2000 mg/kg (typically greater than 5000 mg/kg), and it is non-irritating to skin and eyes, belonging to low-toxicity substances.
| Parameter | Specification/Indicator |
|---|---|
| Chemical Name | Polyethylene Glycol 2000 |
| CAS Number | 25322-68-3 |
| Molecular Formula | H(OCH₂CH₂)nOH |
| Average Molecular Weight | Approximately 2000 |
| Appearance | White to slightly yellow waxy solid or flake |
| Melting Point | Approximately 50–55°C |
| Flash Point | >220°C (closed cup method) |
| Ionic Type | Non-ionic |
| Solubility | Easily soluble in water and various organic solvents |
| Acute Oral Toxicity (LD₅₀) | >2000 mg/kg (rat) |
| Hazard Classification | Non-hazardous chemical |
Pharmaceutical Field: PEG-2000 is a classic pharmaceutical excipient, used as a suppository base, ointment base, and pill base, utilizing its suitable melting range and water solubility to achieve effective drug release and absorption. In tablets, it serves as a binder and lubricant to improve forming and demolding properties; in film coating, it acts as a plasticizer to enhance film flexibility. Additionally, it can be used as a solubilizer for poorly soluble drugs and as a cryoprotectant for protein drugs.
Cosmetics and Personal Care: As an efficient humectant and emollient, it improves the spreadability and skin feel of creams and lotions; it also provides viscosity adjustment and emulsion stabilization, helping to build a fine and stable emulsion system.
Textile Industry: It can be used as an antistatic agent and softening finishing agent, forming a hydrophilic film on the fiber surface to reduce static accumulation and impart a smooth and soft hand feel. In spinning oils, it acts as a smoothing agent and bundling agent to reduce fiber friction.
Coatings, Inks, and Adhesives: In water-based systems, it serves as a dispersant and rheology modifier, helping to uniformly disperse pigments and fillers, and adjust thixotropy and leveling properties. In adhesives, it enhances the flexibility of the bonded layer and extends the open time.
Metalworking Fluids: As a lubricating enhancing component in water-based cutting fluids and grinding fluids, it reduces friction heat while providing rust inhibition and cleaning capabilities. In mold release agents, it utilizes its low thermal decomposition residue and film-forming smoothness to assist mold separation.
Synthetic Intermediates: By reacting terminal hydroxyl groups with fatty acids or ethylene oxide, a series of non-ionic surfactants such as polyethylene glycol fatty acid esters and polyethers can be prepared.