Nucleophilic chain polymerization in which a cyclic monomer yields a monomeric unit that is either acyclic or contains fewer rings than the cyclic monomer.
Example:
Non-ionic monomers used in ring-opening nucleophilic chain polymerization include intramolecular anhydrides of N-carboxy amino acids (commonly referred to as N-carboxy anhydrides or NCAs).
Source:
PAC, 2022, 94, 1093. 'Terminology for chain polymerization (IUPAC Recommendations 2021)' on page 1129 (https://doi.org/10.1515/pac-2020-1211)