Understanding the Microstructure of Poly(p-phenylenevinylene)s Prepared by Ring-Opening Metathesis Polymerization Using 13C-Labeled Paracyclophanediene Monomers

Abstract

Selectively main chain 13C-labeled poly(p-phenylenevinylene)s (PPVs) were synthesized by ring-opening metathesis polymerization (ROMP) of 13C-labeled dialkoxy-substituted [2,2] paracyclophane-1,9-dienes (M) using the Grubbs second generation ruthenium carbene complex (G2). Analysis of the natural abundance and 13C-labeled PPVs by NMR spectroscopy showed no main chain structural defects for these polymers. Comparison of the in situ 1H and 13C NMR spectroscopy during the ROMP of labeled and unlabeled monomer enabled the active ruthenium carbene chain ends present during the initiation and propagation reaction to be definitively characterized. Using 13C NMR spectroscopy, the regiochemistry of the propagation of the asymmetric monomer M with G2 was found to be essentially regiorandom.