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PEO vs PEG
I understand that polyethylene glycol and polyethylene oxide are synonyms but I have also read that typically, materials with molecular weight less than 20,000 g/mol are referred to as PEGs, whereas those with molecular weight above 20,000 g/mol are referred to as PEOs. Are these interchangeable when formulating or due to the difference in molecular weights they aren’t?
If sources only state polyethylene oxide how do I know what type of PEG it is?
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4 Replies
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It’s just a matter of taste, they’re synonyms. Some industries/applications/products call it this, others that way. -
As you state, they are one and same. The INCI convention used in personal care is to name ethoxylated esters as “PEG-” and ethoxylated alcohol ethers as “-eth”. Copolymers of PEO are named as PEG/PPG (w/polypropylene glycol). The drug peeps are enamored with the prefix “PEO”, but its all the same molecule.
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Thanks both. My understanding is that there are many different types of PEGs used in cosmetic formulations but they aren’t all interchangeable, correct?
For formulating cosmetics, if a material was just marketed as a PEO, would I not need to know what PEG it is i.e. PEG20, PEG40, PEG80, PEG90M, PEG180M etc.?
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They’re not interchangeable and yes, you would have to know their degree of polymerisation. Short PEGs are liquid, long PEGs waxy, and very long ones hard like platics (which they are).
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