Polymers of carbonic acid, 21. Ring-opening polymerization of cyclobis(diethylene glycol carbonate) by means of BuSnCl3, SnOct2 or Bu2SnO as catalysts

✍ Scribed by Hans R. Kricheldorf; Martina Lossin; Andreas Mahler

• Publisher: John Wiley and Sons
• Year: 1997
• Tongue: English
• Weight: 518 KB
• Volume: 198
• Category: Article
• ISSN: 1022-1352
• DOI: 10.1002/macp.1997.021981119

✦ Synopsis

Cyclobis(diethy1ene glycol carbonate), (DEGC),, was synthesized by polycondensation of diethylene glycol with diethyl carbonate followed by thermal depolymerization of the crude polycarbonate in vacuo. BuSnCl,-initiated polymerizations of (DEGC)2 in chlorobenzene at 100 "C gave poor results. Therefore, all further polymerizations were conducted at 145°C in bulk. Two series of polymerizations were performed with BuSnC1, as catalyst, so that either the time was varied at constant monomerhitiator ( M / I) ratio, or the M/I ratio at constant time. Two analogous series were conducted with SnOct2. With both catalysts high yields but only moderate molecular weights were obtained. SnOct, yielded polycarbonates having octoate end-groups, which were detected by 'H NMR spectroscopy. (DEGQ2 was also polymerized with Bu2Sn0 at M/I = 200 or 500 with variation of time. The highest yields and molecular weights were obtained at the shortest time, whereas longer times caused rapid depolymerization. Therefore, Bu2Sn0 appeared to be the most reactive catalyst. Both 'H and I3C NMR spectra proved that all poly(diethy1ene glycol carbonates) prepared in this work possess an alternating sequence of ether and carbonate groups.