Polyethylene glycol PEG-4000/6000 (CAS No.: 25322-68-3) is polymerized from ethylene oxide, with the molecular formula HO(C2H4O)nH, a degree of polymerization n approximately between 70 and 200, and a molecular weight range of 3400~6600. At room temperature, the product appears as a white to slightly yellow waxy solid or granules, with a melting point range of 50~63°C. After melting by heating, it becomes a transparent viscous liquid and returns to a solid state upon cooling. This product is a non-ionic surfactant that hardly forms micelles, so its CMC value is "none"—this characteristic makes it more inclined to function as a solubilizer, dispersant, and excipient in formulations, rather than typical micellar solubilization.
From a functional parameter perspective, PEG-4000/6000 has a high HLB value of 18.9~19.0, strong hydrophilicity, and is easily soluble in water. The pH of a 1% aqueous solution ranges from 5.0 to 7.0, which is near neutral and has minimal impact on the pH of the formulation system. The product has high purity (active content ≥99%), with an acid value ≤0.1, saponification value ≤1.0, and iodine value ≤1, indicating stable chemical properties and almost no oxidizable unsaturated bonds or free acids. The hydroxyl value ranges from 8 to 16, which is typical for this molecular weight range and directly relates to the activity of subsequent derivatization reactions. Additionally, the product's surface tension is approximately 55~60 mN/m (1% aqueous solution), cloud point >100°C, flash point >240°C, exhibiting excellent thermal stability and safety under typical processing temperatures.
In terms of safety, PEG-4000/6000 has an acute oral toxicity LD50 > 5000 mg/kg, classified as practically non-toxic, and is not considered a hazardous substance under GHS classification. However, it should be noted that fine dust generated during processing can form explosive mixtures with air (dust explosion class St1); operations must be conducted away from ignition sources and with good ventilation. The product is highly hygroscopic and must be stored in sealed, moisture-proof containers, with a recommended storage temperature of 10~30°C.
| Parameter Name | Technical Indicator | Remarks |
|---|---|---|
| CAS No. | 25322-68-3 | — |
| Molecular Formula | HO(C2H4O)nH, n≈70~200 | — |
| Molecular Weight | 3400~6600 | — |
| Appearance (25°C) | White waxy solid or granules | — |
| Ion Type | Non-ionic | — |
| Melting Point | 50~63°C | — |
| Density | 1.20~1.21 | — |
| HLB Value | 18.9 / 19.0 | — |
| Active Content / Solid Content | ≥99% | — |
| pH (1% Aqueous Solution) | 5.0~7.0 | 25°C |
| pH (5% Aqueous Solution) | 4.5~7.5 | 25°C |
| Moisture Content | ≤1.0% | — |
| Hydroxyl Value | 8~16 mg KOH/g | — |
| Acid Value | ≤0.1 mg KOH/g | — |
| Saponification Value | ≤1.0 mg KOH/g | — |
| Iodine Value | ≤1 | — |
| Amine Value | ≤1 mg KOH/g | — |
| Unsaturation | Saturated, <0.1 mol/kg | — |
| Surface Tension (1% Aqueous Solution) | Approximately 55~60 mN/m | 25°C |
| Cloud Point | >100°C | — |
| Critical Micelle Concentration (CMC) | None (does not form micelles) | — |
| Kinematic Viscosity (100°C, Molten) | Approximately 75~400 mm²/s | — |
| Dynamic Viscosity (100°C) | Approximately 100~500 mPa·s | — |
| Refractive Index (20°C, Molten State) | Approximately 1.45~1.46 | — |
| Flash Point (Open Cup) | >240°C | — |
| Hygroscopicity | Low | Sealed moisture-proof storage |
| Foam Characteristics | Low foaming | — |
| Alkali Resistance | Alkali resistant | — |
| Free Alcohol Content | ≤0.5% | — |