Cyclic polybutadiene via ring-expansion metathesis polymerization (REMP) and measurement of topological purity

Abstract

Recent progress has been made in the synthesis and characterization of cyclic polybutadiene (PBD) prepd. using a ruthenium-based ring-expansion metathesis polymn. catalyst which is tethered to a solid support via from both the N-heterocyclic carbene (NHC) ligand and Hoveyda chelate. This catalyst system was envisioned to produce cyclic polymers from cycloolefin monomers in high purity and with controllable mol. wts. and microstructures. The topol. purity of a series of cyclic PBDs (mol. wts. = 25 - 260 kg/mol) was detd. using temp. gradient interaction chromotagrophy (TGIC) which seperates polymers by topol. Addnl., the cyclic PBD series was characterized rheol. to both quanitfy topol. purity and to measure stress relaxation moduli vs. mol. wt. relationships. An analagous linear series of cyclic PBD was studied and showed different behavior in both soln. and in the melt vs. their cyclic counterparts.