Study On Polyphenylacetylene Catalyzed By The Late Transition Metal And Chloride Of Ln Catalysts

Design and development of novel catalyst systems for the polymerization of substituted acetylenes have been an active area of reseach,aiming at the synthesis of processable and highly functional polymers.Polymerization of phenylacetylene in toluene was catalyzed by a new late transition metal complex catalyst system based on bis-(β-trifluoro ketoamino)nickel(â…¡)/Al(Et)₃.The influence of polymerization conditions such as polymerization temperature,A1/Ni molar ratio,monomer concentration,and polymerization time were investigated.The obtained polymer was characterized by gel permeation chromatography,proton nuclear magnetic resonance, Fourier-transform infrared spectroscopy,differential scanning calorimetry,and wide-angle X-ray diffraction.The results indicated that the catalyst system exhibited definite catalytic activity.The polymerization yielded polyphenylacetylene with moderate molecular weight and molecular weight distribution(M_w/M_n= 1.7-2.2).The polymers own cis-transoidal stereostructure(cis=83.4%) by calculating according to ¹H NMR and are noncrystal via DSC and WAXD analysis.The structure of LaCl₃ and CeCl₃ are similar to WCl₆ and MoCl₅,but LaCl₃ and CeCl₃ have a more outside electronical structure than WCl₆ and MoCl₅.Polymerization of phenylacetylene in DMF and EtOH were catalyzed by Lanthanum chloride/n-BuLi and Cerium chloride/n-BuLi catalytic systems, respectively.The influences of polymerization conditions such as polymerization temperature,Li/La,Li/Ce molar ratio were investigated.The obtained polymer was characterized by gel permeation chromatography,proton nuclear magnetic resonance, Fourier-transform infrared spectroscopy,differential scanning calorimetry,and wide-angle X-ray diffraction.The results indicated that the catalyst system exhibited definite catalytic activity,and the obtained polymer catalyzed by Lanthanum chloride/n-BuLi owning various steterostructures,but the obtained polymer catalyzed by Cerium chloride/n-BuLi owning a possible transoidal stereostructure.