Ring-opening metathesis polymerization of substituted bicyclo[2.2.2]octadienes: a new precursor route to poly(1,4-phenylenevinylene)

Abstract

Poly(1,4-phenylenevinylene) (PPV), a perfectly alternating copolymer of p-phenylene and trans-vinylene units, possesses attractive material properties. Thin films of PPV display high electrical conductivity when doped (σ = 5000 S/cm), a large, third-order nonlinear optical response (χ^3 = 1.5 X 10^(-10) esu), and photo- and electroluminescence in the visible region. However, the extended planar topology of the PPV backbone, which renders it infusible and insoluble in nonreactive media, limits the capacity for post-synthesis fabrication of the material. A convenient method to circumvent this problem consists of a two-step synthesis via a processable intermediate polymer. This precursor polymer can be fabricated into the desired form and subsequently converted to the target polymer by a clean, intramolecular chemical reaction. Wessling and Zimmerman have reported the synthesis of a processable, water-soluble poly(l,4-xylylenesulfonium salt) that undergoes a thermally-induced elimination to PPV under mild conditions.