Poly ethylene glycols (PEGs)
Poly ethylene glycols (PEGs) are family of water-soluble linear polymers formed by the additional reaction of ethylene oxide (EO) With mono ethylene glycols (MEG) or diethylene glycol
The generalized formula for polyethylene glycol is: H(OCH2 CH2) n OH N: Average number of repeating ethylene oxide groups.
There are many grades of PEGs that represents them by theirs average molecular weight. For example, PEG 400 consists of a distribution of polymers of varying molecular weights with an average of 400, which corresponds to an approximate average number of repeating EO groups (n) of ≈9.
Polyethylene glycols are available in average molecular weight ranging from 200 to 8000; this wide range of products provides flexibility in choosing properties to meet the requirements of many different applications.
The most important physical property:
Depend on molecular weight the wide range of the physical property such as solubility , hygroscopic , vapour pressure , melting or freezing point and viscosity are variable :
A: Solubility
Increasing the molecular weight of PEGs results in decreasing solubility in water & solvents.
PEGs are also soluble in many polar organic solvents such as acetone, alcohols.
B: Hygroscopic
PEGs are hygroscopic, it means that they attract and retain moisture from the atmosphere.
Hygroscopic decrease as molecular weight increases.
C: viscosity
PEGs can be considered Newtonian fluids, so the kinematic viscosity of PEGs decreases as temperature increases.
D: Stability
PEGs have low volatility and are thermally stable for limited period
of time below 300°c and without o 2
- Applications:
- Pharmaceuticals:
PEG grades meet requirements of USP/ NF and BP and are widely use in pharmaceutical formulations. As solvent, water soluble, binder, lubricant, plasticizer and use in ointment base, tablet coating, gelatine capsule, liquid oral medications.
- Cosmetics:
As the water soluble , odourless , neutral, hygroscopic, lubricant ,plasticizer, non-volatile , no irritating
properties :
The PEGs are used in wide range of cosmetics and personal care products such as creams , lotions , sticks , cakes , powders , jellies.
- Household products:
Soaps, detergents, polishes & cleaners are main applicant of poly ethylene glycols, because these
products are water soluble & inert, with low volatility and low toxicity.
- Ceramics and tile:
As the plasticizer, lubricity, binders and carriers properties: PEGs are widely use in ceramic and tile industry.
- Adhesives and textile:
As the plasticizer, lubricants, softeners, antistatic agents & conditional agents, PEGs are used in adhesives & textile industry.
