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

Yan Cao, Hui Wu, Yuji Higaki, Hiroshi Jinnai, Atsushi Takahara

Research output: Contribution to journalArticle

7 Citations (Scopus)

Abstract

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 γ-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 γ-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 γ-form of nylon-12 and that the b axis (stem axis) of the γ-form crystals is perpendicular to the long axis of the rod. These results revealed that only lamellae with h0l directions are able to grow inside the nanopores and the growth of lamellae with hkl (k ≠ 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.

Original languageEnglish
Pages (from-to)439-445
Number of pages7
JournalIUCrJ
Volume1
DOIs
Publication statusPublished - 2014 Oct 10

Keywords

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

ASJC Scopus subject areas

  • Chemistry(all)
  • Biochemistry
  • Materials Science(all)
  • Condensed Matter Physics

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