Molecular self-assembly of nylon-12 nanorods cylindrically confined to nanoporous alumina

作者：Cao Yan; Wu Hui; Higaki Yuji; Jinnai Hiroshi; Takahara Atsushi^*

来源：IUCrJ, 2014, 1(6): 439-445.

DOI：10.1107/S2052252514020132

• molecular self-assembly
• nanorods
• selected-area electron diffraction
• cylindrical confinement

Molecular self-assembly of nylon-12 rods in self-organized nanoporous alumina cylinders with two different diameters (65 and 300 nm) is studied with transmission electron microscopy (TEM) and wide-angle X-ray diffraction (WAXD) in symmetrical reflection mode. In a rod with a 300 nm diameter, the tendency of the hydrogen-bonding direction of a gamma-form crystal parallel to the long axis of the rod is not clear because of weak two-dimensional confinement. In a rod with a diameter of 65 nm, the tendency of the hydrogen-bonding direction of a gamma-form crystal parallel to the long axis of the rod is more distinct because of strong two-dimensional confinement. For the first time, selected-area electron diffraction (SAED) is applied in a transmission electron microscope to a polymer nanorod in order to determine the hydrogen-bond sheet and lamellar orientations. Results of TEM-SAED and WAXD showed that the crystals within the rod possess the gamma-form of nylon-12 and that the b axis (stem axis) of the gamma-form crystals is perpendicular to the long axis of the rod. These results revealed that only lamellae with %26lt; hol %26gt; directions are able to grow inside the nanopores and the growth of lamellae with %26lt; hkl %26gt; (k not equal 0) directions is stopped owing to impingements against the cylinder walls. The dominant crystal growth direction of the 65 nm rod in stronger two-dimensional confinement is in between the [-201] and [001] directions due to the development of a hydrogen-bonded sheet restricted along the long axis of the rod.

• 出版日期2014-11