Rigid-rod derived amorphous polydiacetylenes

Abstract

During our investigations of diacetylene monomers that exhibit thermotropic liquid-crystal phase behaviour, it was discovered that spontaneous and rapid thermal polymerization of the isotropic monomer melt takes place with some of the compounds examined. In the diacetylene monomer series containing symmetrically disubstituted 4-oxybenzylidene-4′-n-octylaniline (OBOA) side-groups attached to a butadiyne core via a polymethylene spacer, monomer liquid crystallinity is seen in the lower members of the series yet facile polymerization in the isotropic monomer melt is observed only in the lowest member of the series. This compound, 1OBOA, is believed to be rod-like in structure. It is this microstructural architecture that is believed to be responsible for imparting this unique combination of polymerization and polymer properties. Traditional molecularly flexible diacetylene monomers and the more flexible homologues in the nOBOA series do not show such facile melt-phase reactivity and do not allow the synthesis of purely amorphous conjugated polymer films.