The term polypropylene glycol or PPG is reserved for polymer of low- to medium-range molar mass when the nature of the end-group, which is usually a hydroxyl group, still matters.

The isotactic polymer can be produced from optically active propylene oxide, but at a high cost.

A salen cobalt catalyst was reported in 2005 to provide isotactic polymerization of the prochiral propylene oxide[3] PPG has many properties in common with polyethylene glycol.

This confers some degree of water miscibility though not as good as ethylene oxide based molecules.

[10] It is used to synthesize the epoxy reactive diluent and flexibilizer, Poly(propylene glycol) diglycidyl ether.