Ring-expansion metathesis polymerization of cycloolefins to highly pure cyclic polymers
Abstract
The means to produce cyclic polymers in high purity and at large scale remains an elusive goal. Although ring-closure methods have been successful in producing rings free of linear chains, scalability is an unavoidable obstacle. We report a ring-expansion method for synthesizing cyclic polyalkenamers in high purity and at scale ( > 25 g / reaction) using a recyclable heterogeneous ruthenium-based olefin metathesis catalyst. This ring-expansion metathesis polymn. (REMP) catalyst is an analog of the 2nd Generation Hoveyda-Grubbs catalyst and is covalently bound to a silica surface via dual tethers from the N-heterocyclic carbene (NHC) and benzylidene. Cyclic polyalkenamers were synthesized from a variety of cycloolefins, including cyclopentene and cyclooctadiene. Their purity from linear species was detd. using rheol., hightemp. HPLC (HT-HPLC), solid-state NMR, size-exclusion chromatog. (SEC), and differentional scanning calorimetry (DSC). This synthetic methodol. was shown to be a robust means to produce cyclic polymers in high purity and at large scale.
Additional Information
© 2016 American Chemical Society.Additional details
- Eprint ID
- 70390
- Resolver ID
- CaltechAUTHORS:20160916-092421211
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2016-09-29Created from EPrint's datestamp field
- Updated
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2020-03-09Created from EPrint's last_modified field