Diphenylacetylene was polymerized by di(cyclpentadienyl) titanium dichloride with irradiation of light over 423K.The structure and properties of poly (DPA) were studied by using IR

MS

thermal analysis

X-ray crystalline diffraction and electrical conductivity measurements.The poly (DPA)-A was rigid

cis -cisoidal

pseudohexagonal packing of rodlike molecules and crystallized over 95%.The first crystalline diffraction peak was at 2θ=7.1°.The lateral spacing 1.26nm

calculated from the diffraction pattern

can be interpreted as the (10 10) diffraction of the pseudohexagonal lattice.The nearest chain-to-chain distance or the diameter of the molecule was 1.46nm.The IR absorption at 1179

1156cm-1was due to the cis-cisoidal characteristic vibration.The activation energy of the polymerization was 2.6×105J/mol.The crystalline poly(DPA) was stable up to temperatures varying between 493K and 573K.Only one endothermic peak that occurred at 713K was observed witha a weight loss of polymer up to 10% This endothermic peak is explained in terms of the melting of the polymer

hydrogen migration and scission of the main chain The poly (DPA)was not obtained in the presence of diphenyl ketone or DMSO at 443K.The pathway of the polymerization was discussed.