Methods for forming polycarbonate ether polyols and high molecular weight polyether carbonates

The method of preparing the polycarbonate ether polyol or high molecular weight polyether carbonate using controlled addition of materials during polymerisation includes the steps of:mixing catalyst of formula(I), double metal cyanide (DMC) catalyst and optionally carbon dioxide and/or solvent with epoxide and optionally starter compound and/or carbon dioxide; ormixing DMC catalyst and optionally starter compound, carbon dioxide and/or solvent with epoxide and optionally carbon dioxide and/or solvent; ormixing epoxide, catalyst of formula(I), starter compound and carbon dioxide and optionally solvent; ormixing catalyst of formula (I), DMC catalyst and optionally starter compound, epoxide, carbon dioxide and/or solvent to form in each case a mixture (α); andadding one or more of starter compound, epoxide, carbon dioxide, catalyst of formula(I), DMC catalyst and/or solvent to mixture (α) to form mixture (β) comprising starter compound, epoxide, carbon dioxide, catalyst of formula(I), DMC catalyst and optionally solvent,