PEG 400

PEG 400 or Polyethylene Glycol 400 is a low molecular weight grade of polyethylene glycol and is marketed by Dow Chemicals under the trademark name of Carbowax. It is a thick, hygroscopic, and colorless liquid substance widely used in lots of medical formulas due to its low toxicity. 

PEG 400 is hydrophilic and is miscible with water, alcohol, benzene, glycerin, acetone, aromatic hydrocarbons, and other glycols, while it is slightly soluble in aliphatic hydrocarbons. This property makes it a suitable additive for lotions and body creams. It absorbs easily on the skin, rendering it smooth without dehydrating. Because of its high molecular weight, boiling point, and specific heat, PEG 400 is the preferred medium in hot bath applications.

General Information:

IUPAC nomenclature – polyethylene glycol

CAS number – 25322-68-3

Molecular formula – C_2nH_4n+2O_n+1, n=8.2 to 9.1

Molar mass – 380-420 g/mol

OH value – 268-294

Density – 1.128 g/cm³

pH of 5% aqueous solution – 4-7

Melting point – 4-8°C

Freezing point – 4-10°C

Viscosity – 90.0cSt at 25°C, 7.3cSt at 99°C

Flash point - 238°C

LD₅₀ – 30 ml/kg, orally in rats

Common Uses:

• Tire manufacturing lubricant
• Paper softener
• Plasticizer for sponges and synthetic leather
• Ink solvent and lubricant for print heads of Hewlett-Packard DesignJet printers
• Wetting agent for soaps and dispersant for toothpastes
• Anti-curl agent
• Soldering flux
• Intermediate in resin production
• Additive in pharmaceutical formulations containing sulfur, hydrocortisone, methyl salicylate, nitrofurazone, etc.