Study on the cationic polymerization mechanism of 1,3-dioxepane in the presence of ethylene glycol

✍ Scribed by Ye Liu; Hengbin Wang; Caiyuan Pan

• Publisher: John Wiley and Sons
• Year: 1997
• Tongue: English
• Weight: 446 KB
• Volume: 198
• Category: Article
• ISSN: 1022-1352
• DOI: 10.1002/macp.1997.021980819

✦ Synopsis

Abstract

The cationic polymerization of 1,3‐dioxepane (DOP) initiated with trifluoromethanesulfonic acid (I) in the presence of ethylene glycol (EG) was investigated. At sufficiently low concentration of the initiator ([I] > 0.01 mol/L vs. [EG] < 0.20 mol/L), the molecular weights of the obtained polyacetal oligodiols are controlled by the mole ratio of consumed DOP to initial EG. Gel‐permeation chromatography studies revealed that the concentration of cyclic oligomers in the products are negligible. The mechanism of the polymerization was investigated by means of kinetic studies. The results showed that the polymerization proceeds according to the active chain end mechanism (ACF) in combination with the activated monomer mechanism (AM); thus the cyclic oligomer in the obtained polymer is reduced, and intermolecular chain transfer to EG in ACE is dominant. It was also demonstrated that as [DOP]^2^[I]/[EG] decreases the contribution of ACE to the polymerization decreases and that of AM increases. In addition, ^1^H and ^13^C NMR data illustrated that each macromolecule of polyDOP oligodiols contained one EG unit on average and that no EG end groups exist.