二氯二茂钛引发二苯乙炔聚合的研究

STUDY ON THE POLYMERIZATION OF DIPHENYLACETYLENE BY DI(CYCLOPENTADIENYL) TITANIUM DICHLORIDE WITH IRRADIATION OF LIGHT

在高温下 ,二氯二茂钛受光照引发二苯乙炔聚合 ,得到结晶度为 95 %的聚二苯乙炔 .经红外、质谱、热分析、X光衍射、元素分析等方法 ,确定其结构为顺顺式螺旋刚性棒状结构 ,形成假六方晶系堆积 ,螺旋柱直径即螺旋轴间距为 1 46nm ,其特征红外吸收峰位于 1179cm-1和 115 6cm-1.在聚合引发阶段中止反应 ,分离出聚合中间体六苯基苯 .根据不同温度时聚合转化率与时间的关系曲线 ,测得聚合活化能为 2 6× 10 5J/mol.热分析表明 ,结晶聚二苯乙炔在 493K至 5 73K比较稳定 ;在 713K的吸热峰显示出破坏晶格的能量 .根据聚合反应诱导期长、中间体和聚合物的结构以及阻聚反应 ,推断聚合过程中二氯二茂钛受光照产生二氯化钛 ,催化二苯乙炔进行均相定向聚合 .结晶聚二苯乙炔电导率小于 10 -12 (Ωcm) -1.

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 1 0) 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 -1 was due to the cis \|cisoidal characteristic vibration.The activation energy of the polymerization was 2.6×10 5J/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.The exothermic peak occurred just after the melting point was related with the cis \|to\| trans change,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.