Preparation and properties of functional polymers from acetylene derivatives

Abstract

(Z)-1-Methoxy-4-phenyl-1-buten-3-yne (MPBEY), 1,4-diphenyl-1-buten-3-yne (DPBEY), 5-(2-pyridyl)-2,4-pentadiyn-1-ol (PyPDO) were polymerized over $NbCl_5$- or $TaCl_5$- based catalysts followed by pyrolysis to obtain graphite-like pyropolymers. The brown metathesis polymer, poly[(Z)-1-methoxy-4-phenyl-1-buten-3-yne] [poly(MPBEY)], has the structure of fully conjugated backbone and was converted into black polyacene-based polymer on pyrolysis. The metathesis polymerization is influenced by substituents directly attached to the acetylene moiety. The structure of the polymers is also influenced by oxygen. The brown metathesis polymer, poly(1,4-diphenyl-1-buten-3-yne) [poly(DPBEY)] was annealed at $250^\circ$C to obtain partially crosslinked polymer which showed 20% increase of carbon residue on pyrolysis over $400^\circ$C than the pyrolyzed poly(1,4-diphenyl-1-buten-3-yne) without annealing. The black metathesis polymer, poly[5-(2-pyridyl)-2,4-pentadiyn-1-ol] [poly(PyPDO)], has the structure of fully conjugated backbone and was converted into polyacene-based polymer having pyridyl pendant group. The pyropolymers prepared by vacuum pyrolysis over 700℃ have nitrogens incorporated into graphene sheets. Four kinds of synthetic carbons were prepared by vacuum pyrolysis of black polyacene-based polymers. The carbonization yields are influenced by the substituents in the precursor polymers. The electrochemical properties of carbons were dependent on the polymers. The relationship between the structure of synthetic carbons and electrochemical behavior was investigated by TEM and CD studies. 3,5-Dinitrobenzoates of poly[1-(n-methoxyphenyl)penta-1,3-diyn-5-ol] [DN-1,n-PMDO, (n = 2,4)] are prepared by the reaction of (1,n)-PMDO (n = 2,4) and 3,5-dinitrobezoyl chloride. DN-1,2-PMDO shows high initial potential and low photoconductivity, while DN-1,4-PMDO shows low initial potential and high photoconductivity. The photoconductivity of DN-1,2-PMDO could be improved by introduc...