Metathesis “rainbow” polymerizations--a systematic route into polyene sequences

• Published in: Synthetic metals 1989-02, Vol.28 (3), p.D105-D108
• Main Authors: Klavetter, F.L., Grubbs, R.H.
• Format: Article
• Language: English
• ISSN: 0379-6779; 1879-3290
• DOI: 10.1016/0379-6779(89)90679-6

Metathesis polymerization of 1,3,5,7-cyclooctatetraene (COT) yields an intractable, silvery conducting polymer (polyacetylene). Metathesis polymerization of 1,5-cyclooctadiene (COD) affords a rubbery, transparent insulating polymer (poly-butadiene). What material results upon co -polymerization? Since COD and COT undergo metathesis polymerization at similar rates, the resulting copolymer should have a random distribution of ring-opened COD (CCCCCCCC) and and ring-opened COT(CCCCCCCC) units along the polymer backbone. The greater the concentration of COD in the COD/COT monomer mixture, the more sites of saturation randomly inserted in the polymer backbone. By controlling the COT/COT ratio, copolymers with varying conjugation lengths are produced. Raman spectroscopy, UV-Vis, NMR, electrical conductivity, and non-linear optical measurements all indicate a progression of conjugation length in the copolymer with increasing mol fraction COT in the COD/COT mixture. As an important control study, copolymers formed from norbornene (NBE) and COT-- which undergo metathesis polymerization at very different rates--have also been investigated.