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Determination of the Tacticity of Ring-opened Metathesis Polymers of Norbornene and Norbornadiene by13C NMR Spectroscopy of their Hydrogenated Derivatives
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1996
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Organic Material ChemistryChemical EngineeringRing-opened Metathesis PolymersPropagation ReactionNmr SpectroscopyEngineeringHeterocyclicAlkene MetathesisPolymer ScienceOrganic ChemistryFine StructureChemistryBiomolecular EngineeringPolymer ReactionPolymer ChemistryPolymer SynthesisPolymers
The 125 MHz 13C nuclear magnetic resonance (NMR) spectra of the hydrogenated derivatives of ring-opened metathesis polymers (ROMP) of bicyclo[2.2.1]hept-2-ene (norbornene) and bicyclo[2.2.1]hepta-2,5-diene (norbornadiene) prepared using a range of initiators, have been analysed in detail. The signals due to the methylene carbon atoms in the enchained cyclopentyl rings of these polymers show fine structure which is assigned to m and r ring dyads and mm, mr/rm and rr ring triads, enabling the tacticity of the hydrogenated polymer, and thus of the polyolefin precursor, to be determined for high-cis or high-trans polymers. Novel methods for making high-cis polymers are described and solvent-dependent variations in the stereospecificity of the propagation reaction have been observed.