Methods of ring opening polymerization and catalysts therefor

A method, comprising:

• forming a mixture comprising a cyclic carbonyl monomer, a nucleophilic initiator, an optional accelerator, an optional solvent, and an oxoacid, the oxoacid comprising one or more active acid groups, the active acid groups independently comprising a carbonyl group (C═O), sulfoxide group (S═O), and/or a phosphonyl group (P═O) bonded to one or more active hydroxy groups;
• and
• adding to the mixture a nitrogen base comprising one or more guanidine and/or amidine functional groups, thereby forming a salt catalyst, wherein a ratio of moles of the active hydroxy groups to moles of the guanidine and/or amidine functional groups of the salt catalyst is greater than 0 and less than 2.0,
• allowing the salt catalyst to catalyze ring opening polymerization of the cyclic carbonyl monomer, thereby forming a polymer.