Article Cite This: Macromolecules XXXX, XXX, XXX−XXX
Understanding the Microstructure of Poly(p‑phenylenevinylene)s Prepared by Ring-Opening Metathesis Polymerization Using 13 C‑Labeled Paracyclophanediene Monomers Dharam R. Kumar, Benjamin J. Lidster, Ralph W. Adams, and Michael L. Turner* School of Chemistry, University of Manchester, Oxford Road, Manchester M13 9PL, United Kingdom S Supporting Information *
ABSTRACT: Selectively main chain 13C-labeled poly(pphenylenevinylene)s (PPVs) were synthesized by ring-opening metathesis polymerization (ROMP) of 13C-labeled dialkoxysubstituted [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.
■
labeled 13C PPVs, synthesized by both the sulfinyl and Gilch methods. In PPVs prepared by the Gilch route, the tolane− bisbenzyl unit (11.2%) was again a major defect. Additionally, other defects identified included non-eliminated groups (1.8%), chloro−vinyl bonds (∼1.4%), aldehydes (∼0.1%), and carboxylic acids (∼0.2%). In addition, high levels of residual sulfinyl groups (6.9%) were found in PPVs prepared by this method. These could be reduced to
