Polypropylene glycol or polypropylene oxide is the polymer of propylene glycol. Chemically it is a polyether, and, more generally speaking, it's a polyalkylene glycol (PAG).
P 3744 (OTTO) Polypropylene glycol 2000 Cas 25322-69-4 - used as a surfactant, wetting agent, dispersant in leather finishing. P 2020 (OTTO) Polypropylene glycol 2000 Cas 25322-69-4 - used in many formulations for polyurethanes. P 2020 (OTTO) Polypropylene glycol 2000 Cas 25322-69-4 - used as a rheology modifier.