A series of comblike N-alkylated poly (p-phenylene terephthamide) comb-like polymers(denoted as PPTACns, n = 8, 10, 12, 14, 16, 18, number of carbon atoms in alkyl side group) with rigid main chain was prepared using N-alkylated method. The methods of DSC, XRD and FT'IR were utilized to investigate the packing behavior of the rigid main chain, conformation of the comblike polymer and thermal behavior, and the correlation between these properties with the alkyl side chain length. The results of XRD and DSC indicate that the alkyl side chains crystallize when the carbon number of the side chain reaches 14. The XRD results indicate that PPTACns have layered structure and their layer spacing depends on the carbon number of the side chain. The FTIR results indicate that the conformation of the PPTACns molecular chain is affected by the variation of the crystalline state of the alkyl side chain. For PPTACns with crystallized alkyl side chain, the conformation of the molecular chain undergoes an obvious change as the side chain is melt. The peak position of νc=0 and γ=c_H bands in PPTACns with molten alkyl side chain are similar to that of PPTACns with non-crys-tallizable alkyl side chain.%基于聚对苯二甲酰对苯二胺( PPTA),采用N-烷基化方法制备了系列PPTACns(烷基侧链碳原子数n=8,10,12,14,16,18)刚性主链梳状高分子,利用DSC,XRD和FTIR等方法研究了其主链堆积行为、分子链构象及热性能等与烷基侧链长度及结晶特性之间的关系.XRD和DSC结果表明,当烷基侧链碳原子数达到14时,烷基侧链发生结晶.XRD结果显示,PPTACns具有层状结构,烷基侧链长度对主链层间距影响显著.FTIR研究发现,烷基侧链的聚集状态对PPTACns分子链的构象产生较大影响,伴随着烷基侧链结晶的熔融,PPTACns的分子链构象发生显著改变.烷基侧链处于熔融状态的PPTACns的vC=O和γ=C-H谱带峰位与烷基侧链不结晶的PPTACn接近.
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