Abstract: 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 FTIR 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 ν_C=O and γ_C-H bands in PPTACns with molten alkyl side chain are similar to that of PPTACns with non-crystallizable alkyl side chain.

Key words: N-Alkylated poly(p-phenylene terephthamide), Comblike polymer, Rigid main chain, Alkyl side chain