The chemical structure of polyethylene glycol PEG-8000 (CAS number: 25322-68-3) is generally represented as H(OCH₂CH₂)nOH, where n denotes the number of repeating oxyethylene units (-OCH₂CH₂-). The "8000" in PEG-8000 indicates its average molecular weight of approximately 8000, corresponding to a degree of polymerization n of about 180. It is produced by ring-opening polymerization of ethylene oxide with water or ethylene glycol as the starting material, under the action of a catalyst. The final product has a hydroxyl group (-OH) at each end of the polymer chain, imparting good reactivity and water solubility.
As a single-component, nonionic water-soluble polymer, PEG-8000 is not a blended mixture; its main component is the polyethylene glycol homopolymer itself, typically with a purity above 99%. The product appears as a white waxy solid or free-flowing powder, which becomes a colorless transparent liquid upon melting. It exhibits excellent chemical stability and biocompatibility, and is recognized as a safe material with low toxicity and low irritation.
| Parameter Name | Typical Value/Description |
|---|---|
| Main Component | Polyethylene Glycol Homopolymer |
| CAS Number | 25322-68-3 |
| Chemical Formula | H(OCH₂CH₂)nOH |
| Average Molecular Weight | 7000~9000 (Nominal 8000) |
| Molecular Structure | Linear dihydroxy-terminated polyether |
| Ionic Type | Nonionic |
| Appearance | White waxy solid or free-flowing powder |
| Solubility | Highly soluble in water; compatible with many organic solvents |
| pH Tolerance Range | Stable over a wide pH range |
| Acute Toxicity (Rat Oral LD₅₀) | > 50,000 mg/kg |
As a high-purity, stable single-component polymer material, PEG-8000 is widely used in pharmaceuticals (ointment bases, suppository bases, tablet lubricants), cosmetics (moisturizers, emulsion stabilizers), coatings and inks (pigment dispersants), rubber and plastics (mold release agents, antistatic agents), metalworking fluids (lubricants), textiles (sizing agents, antistatic agents), papermaking (gloss agents), agriculture (water-dispersible granule carriers), and biotechnology (protein precipitation and crystallization, cell fusion promoters), among many other fields.
Due to its nonionic nature, PEG-8000 maintains stable performance under various pH conditions and hard water, without adverse reactions with other formulation ingredients, making it an ideal inert functional additive and carrier material.