Most Polyethylene glycols differ only in their molecular weights, hydroxyl numbers and viscosity profiles. Polyethylene glycols are named based on the number of units of ethylene glycol, or on their molecular weights.
Low molecular weight Polyethylene glycols are in the liquid state while higher molecular Polyethylene glycols exist as waxy solids. Pharmaceutical and cosmetics use Polyethylene glycols with smaller molecular weights. The lower the molecular weight, it helps the active compounds to penetrate the skin. In cosmetic application, Polyethylene glycols (Polyethylene glycols) can function in three different ways: as emollients which helps to soften and lubricate the skin; as emulsifiers which help mix water- and oil-based ingredients thoroughly, and as delivery vehicles that help transport other ingredients deeper into the skin.
Polyethylene glycols or Polyethylene glycols are used in drug delivery systems because they are neutral, nontoxic, and water soluble and can form micelles which are biocompatible and biodegradable.
Polyethylene glycol 4000 (commonly refered to as Polyethylene glycol 4000) typically exists as white to off white flaky solid with a hydroxyl number of 28-36 mg KOH/g and approx. mol weight of 3100-4010. The solubility of a 5% solution is clear and colourless. These Polyethylene glycol polymers are used in a wide variety of products including bath products, shaving products, skin care products, makeup, skin cleansing products, shampoo, hair conditioners and deodorants. Esteem Industries manufactures technical grade while its subsidiary Avesta Pharma manufactures PEG/Macrogol 4000 for supply to European markets.
PEG 6000 (CAS No. 25322-68-3) is a derivative of Polyethylene glycol having white to off white color and available in solid flakes or powder form. The melting range for Polyethylene glycol 6000 is between 58-63 oC and the average molecular weight can be within 5000-7000. Due to its lamellar structure, it may find use in pharmaceutical production of pills and tablets as binder or dry lubricant. Polyethylene glycol-6000 also finds use in enbalming of histological and other medical specimens when dissolved in lower glycols in place of paraffin wax. In cosmetics, Polyethylene glycol 6000 due to its binding property finds use in facial makeup and as wetting agents to inhibit soap cracking. The non-ionic property of Polyethylene glycol 6000 can facilitate the even distribution of electrolytes in galvanic baths for copper & nickel electroplating of steel and iron parts when added as a component. It can also function as anti-dusting agent for after-bath talcum powder, lubricant in paper industry, as a tyre mounting agent , as an additive in grease , as plasticiser in synthetic resin , as enhancer of thermal stability in adhesive preparations. In the rubber industry Polyethylene glycol 6000 at loading of 3-20% may function as mold release agent.
PEG 8000 (CAS No. 25322-68-3) is a Polyethylene glycol having white to off white color and available in solid flakes or powder form. Its high molecular weight mainly prompts its use in pharmaceutical formulations as solvent for oral, topical and parenteral preparations. The high molecular weight Polyethylene glycol 8000 is soluble in water and organic solvents such as alcohols. It can blend with other PEG molecular weights to achieve the desired viscosity properties. Polyethylene glycol 8000 is quite stable and does not support microbial growth, even in aqueous solutions.
Polyethylene glycol 12000 is a colourless polymer of ethylene oxide with an average molecular weight of 12000. This flaky material melting between 57-64oC is highly water soluble and functions as excellent solubilizers. Like most other Polyethylene glycols it is soluble in organic solvents, water and aromatic hydrocarbons and has limited solubility in aliphatic hydrocarbons. Therefore it can be used in a wide variety of home care applications like dish wash, fabric and laundry detergents, hard surface cleaning, in waxes and polishes and large scale industrial & institutional applications. Apart from these applications polyethylene glycol 12000 also functions as a dispersant, in toothpastes, is used to modify therapeutic proteins and peptides to increase their solubility. In analytical applications like gas chromatography, it can function as a polar stationary phase. It is also useful in preserving objects obtained from the ocean. polyethylene glycol 12000 finds application in blood banking as a potentiator, which is used to detect antigens and antibodies.
PEG 20000 S (CAS No. 25322-68-3) is a solid Polyethylene glycol with a mean molecular weight of 20000 available in flake form. The high moleculat weight provides several benefits like excellent solubility in water, low moisture content, highly compatible with hard water, non-volatile non-toxic and generally safe. It belongs to non-hazardous substance or mixture according to Regulation (EC) No. 1272/2008 of the European Union. Considering the safety profiles, studies with drugs like simvastatin for improving their solubility were tested with Polyethylene Glycol 6000, 12000 and 20000. These studies indicated higher phase solubility of drug and could influence the drug dissolution rate from such dispersion mixtures.