Hybrid polyester-polyether polyols

A process for preparing a hybrid polyester-polyether polyol comprising

• reacting a carboxyl group-containing component and an epoxide component selected from ethylene oxide (EO), propylene oxide (PO), butylene oxide, 1-octene oxide, cyclohexene oxide, or styrene oxide, in the presence of one or more of a superacid catalyst and/or a metal salt of a superacid catalyst, a tertiary amine catalyst selected from the group consisting of 2-ethylbutyldiisopropyl amine, triisopropylamine, bis(tert-butyl)methyl amine, and combinations thereof, and optionally a double metal cyanide catalyst,
• under conditions such that a hybrid polyester-polyether polyol, having, as properties induced by the reaction, a polydispersity index that is less than 1.5, an unsaturation that is less than 0.01 meq/g, and an acid number that is less than 2.0 mg/g as potassium hydroxide, is formed,
• wherein the superacid catalyst and/or the metal salt of a superacid catalyst is present in an amount ranging from 10 to 10,000 parts per million, based on the weight of the hybrid polyester-polyether polyol, and polydispersity index is defined as the weight average molar mass/number average molar mass ratio as determined by gel permeation chromatography, unsaturation is determined according to ASTM D4671, and acid number is measured as potassium hydroxide mg/g according and determined by potentiometric titration of a methanolic solution of the sample with standard methanolic KOH solution.