| 초록 |
The crystal structure of poly(2-cyano-1,4-phenylene terephthalamide) (CyPPTA) was studied using wide angle X-ray, IR, and molecular modeling methods. Well-oriented fibers were successfully spun in the liquid crystalline phase of 5 % DMAc/LiCl solution. From the fiber X-ray pattern, 19 reflections were resolved and could be indexed with orthorhombic unit cell parameters of a=9.44Å, b=5.06Å and c=12.92Å. Two chains are in the unit cell and have the glide plane symmetry by the space group of P11n. The unit cell of CyPPTA is similar to the poly(p-phenylene terephthalamide) (Kevlar) with dilation of a axis due to the bulky –CN groups. The molecular modeling shows that the -C=O--H-N inter-chain hydrogen bonds are along the ac planes similar to Kevlar. The geometry in the crystal shows that the -C≡N--H-N inter-chain hydrogen bonds are also possible. These two hydrogen bonds may lead the three-centered one. These hydrogen bonds were confirmed by IR experiments. |
