An improved synthesis of polyacetylene

Abstract

Ring-opening metathesis polymerization of 3,6-bis(trifluoromethyl)pentacyclo[6.2.0.O*~~.O~~~.O~~~]dec-9-ene gives a soluble polymer which is stable at room temperature and is converted into hexafluoroxylene and polyacetylene on heating.Conjugated polymers usually display insulator or poor semiconductor behaviour, but often they can be reversibly modified by electron-transfer reactions to provide materials which display conductivities characteristic of n-or p-type semi-conductors or metals depending on the kind and extent of modification.' Polyacetylene is the paradigm for this field of research and the overwhelming majority of studies have been carried out on a material produced by direct polymerization of acetylene using a technique first described by Shirakawa.2 This material, 'Shirakawa polyacetylene ,' is usually obtained in the form of an open fibrillar mat with a density of ca. 0.4 g cm-3 and variable amounts of catalyst residuel.3 which may have important effects on the observed properties of the material.4 During the last few years we have developed an alternative effective two-stage synthesis of polyacetylene via a soluble precursor polymer (Scheme 1) .5--7 This approach allows the problems of regulating the polymer morphology and purity to be tackled. It is now clear that the material R2 L Scheme 1. A two-stage route to polyacetylene, see refs. 5-7. R Scheme 2. Summary of the photochemistry of the tricyclo[4.2.2.02.']deca-3,7,9-triene system, see refs. 13-16.

Synthesis, processing and material properties of conjugated polymers

“…In order to produce a precursor polymer which was stable at room temperature a large number of prepolymers were examined but the majority of these possessed either insufficient or excessive thermal stability 37. The synthesis of a precursor polymer with good room temperature stability 40 Schrock and co-workers 41 have developed a series of well defined ROMP initiators of the type M(CH-t-Bu) (NAr)(O-t-Bu)2 in which M = W or Mo and Ar = 2,6-CrH3-i-Pr2 which allows better control over this polymerization reaction. Using these systems polyacetylene prepolymers of controlled molecular weight and polydispersities close to unity can be prepared.…”

Ring‐Opening Metathesis Polymerization (ROMP) and Related Processes

“…An effective and widely adopted solution to this problem is the Durham precursor route (Edwards et al, 1984;Feast and Winter, 1985) to polyacetylene, in which a tricyclic triene monomer is subjected to ROMP at the cyclobutene double bond using a WCl 6 /Me 4 Sn catalyst to give a high molecular weight soluble precursor polymer, which can be purified and analyzed using standard polymer characterization techniques. The precursor can then be converted in a controlled manner to polyacetylene in a variety of morphologies (Bott et al, 1985(Bott et al, , 1986Edwards et al, 1984;Feast and Winter, 1985) by a symmetry allowed elimination of hexafluoroxylene (Fig.…”

“…The precursor can then be converted in a controlled manner to polyacetylene in a variety of morphologies (Bott et al, 1985(Bott et al, , 1986Edwards et al, 1984;Feast and Winter, 1985) by a symmetry allowed elimination of hexafluoroxylene (Fig. 3-29).…”

History of Conductive Polymers

“…Among the more successful synthetic procedures were those developed by Feast at Durham, [36] who developed a ring-opening synthesis procedure for polyacetylene derivatives. Meanwhile Naarmann at BASF showed the benefits of dissolving the ZieglerNatta organometallic catalyst in a viscous solvent [37].…”