𝔖 Bobbio Scriptorium
✦   LIBER   ✦

Ring-opening polymerization of cyclic urethanes and ring-closing depolymerization of the respective polyurethanes

✍ Scribed by Stephan Neffgen; Helmut Keul; Hartwig Höcker

Publisher
John Wiley and Sons
Year
1996
Tongue
English
Weight
487 KB
Volume
17
Category
Article
ISSN
1022-1336

No coin nor oath required. For personal study only.

✦ Synopsis

Abstract

The cationic ring‐opening polymerization of trimethylene urethane (tetrahydro‐2 H‐1,3‐oxazin‐2‐one) in the melt with methyl trifluoromethanesulfonate as initiator results in poly(trimethylene urethane) in yields of ≈70%. Under the same reaction conditions 2,2‐dimethyltrimethylene urethane (5,5‐dimethyltetrahydro‐2__H__‐1,3‐oxazin‐2‐one) cannot be polymerized. Poly(2,2‐dimethyltrimethylene urethane), however, was obtained via polycondensation polymerization. Both polymers exhibit a uniform microstructure as deduced from NMR spectroscopic analysis. Ring‐closing depolymerization in the melt with dibutyltin dimethoxide or titanium tetraisopropoxide at 140°C results the respective monomers in yields of ≈90%.

📜 SIMILAR VOLUMES

Ring-opening polymerization of six- and
Ring-opening polymerization of six- and seven-membered cyclic pseudoureas
✍ Masatoshi Miyamoto; Keigo Aoi; Takeo Saegusa 📂 Article 📅 1997 🏛 John Wiley and Sons 🌐 English ⚖ 277 KB 👁 2 views

The cationic ring-opening polymerization of six-membered cyclic pseudoureas, 2-(1-pyrrolidinyl)-( 2a) and 2-morpholino-5,6-dihydro-4H-1,3-oxazine ( 2b), was examined, which proceeded in two different ways, depending on the nature of initiator. The polymerization of 2 with methyl p-toluenesulfonate o