PM - Propylene Glycol Monomethyl Ether — Frequently Asked Questions

Because the two isomers differ toxicologically. Reacting propylene oxide with methanol can place the methyl group at either end, giving the alpha isomer with the hydroxyl on a secondary carbon or the beta isomer with it on a primary carbon. Only the beta isomer is metabolised to a methoxypropionic acid analogous to the harmful ethylene-series metabolites. Commercial PM is specified above 99.5 percent alpha for that reason.

In most applications, yes. It offers comparable solvency, full water miscibility and a similar evaporation rate, and it carries no reproductive toxicity classification. It has been the standard substitution across coatings, inks and cleaning for many years. Some reformulation may be needed since the two are not identical in resin solubility, but the change is well established.

It dissolves the photoresist polymers used in photolithography, wets silicon uniformly and evaporates cleanly without leaving residue, and its favourable toxicological profile matters in a cleanroom environment. High-purity electronics grades are specified with metals controlled at parts per billion and particle counts specified, well beyond industrial grade requirements.

Yes, these are alternative names for propylene glycol monomethyl ether, CAS 107-98-2. PGME is the common technical abbreviation and Dowanol is a trade name. As with all solvents, the CAS number and the alpha isomer specification are the reliable identifiers rather than the trade name.