Chain‐growth limiting reactions in the cationic polymerization of 3‐ethyl‐3‐hydroxymethyloxetane

3‐Ethyl‐3‐hydroxymethyloxetane (EOX) polymerizes readily to branched multihydroxyl polyethers. Molecular weights of the polymers are, however, limited, and macromolecules are predominantly cyclic. This indicates that intramolecular chain transfer to polymer (back‐biting) proceeds in the system. Repeating units in poly‐EOX contain two nucleophilic sites that may participate in back‐biting, namely ether groups and hydroxyl groups. Analysis of matrix‐assisted laser desorption/ionization time‐of‐flight (MALDI‐TOF) mass spectra of poly‐EOX prepared in the presence of analogous polyether that does not contain HO? groups (poly(3,3‐dimethyloxetane)‐poly‐DMOX) shows that the ether group in the repeating unit of poly‐DMOX does not participate in chain transfer to the polymer. However, when DMOX was polymerized in the presence of poly‐EOX, clear evidence of participation of HO? groups in intramolecular chain transfer was obtained. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 245–252, 2004