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Hierarchical structure of the triclinic α-phase crystal in nylon 6,12 mediated by two-dimensional confinement

Authors :
Shichen Yu
Ziwei Lai
Hiroshi Jinnai
Yan Cao
Nan Zheng
Masaki Ageishi
Shuailin Zhang
Source :
Journal of Applied Crystallography. 53:27-33
Publication Year :
2020
Publisher :
International Union of Crystallography (IUCr), 2020.

Abstract

It has been recognized that macromolecular chains can self-assemble into a hierarchical structure from lamellae to spherulites in bulk crystallization. However, little account has been taken of crystal symmetry effects on the hierarchical nanostructure in polymers under cylindrical confinement. In this research, a model polymer, nylon 6,12, most commonly occurring in the triclinic α phase, was chosen in order to demonstrate the effect of triclinic symmetry on the 2D-constrained polymer nanostructure. The self-arranging unit of nylon 6,12 takes various forms, including stems, unit cells, hydrogen-bonded sheets, lamellae and complex spherulites, which is an essential structural feature for investigating hierarchical nanostructure. The rod nanostructure in confinement was examined by cross-checking electron and X-ray diffraction techniques. It is found that the a* axis of the α-phase cell is inclined at about ±6–11° to the rod long axis within the a*b* plane around the c axis (c axis ⊥ rod long axis). The rotation of the a*b* plane most likely results from the impact of the triclinic symmetry on the molecular chain packing under 2D confinement. A mechanism for this a*b* plane tilting is proposed.

Details

ISSN :
16005767
Volume :
53
Database :
OpenAIRE
Journal :
Journal of Applied Crystallography
Accession number :
edsair.doi...........ffcc215ee25b29063ddb9496830571e1
Full Text :
https://doi.org/10.1107/s1600576719014705