二氯二茂钛引发二苯乙炔聚合的研究

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.

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

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 (1010) 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 2.6×105J/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.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.