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Hierarchical structure of the triclinic α‐phase crystal in nylon 6,12 mediated by two‐dimensional confinement
Author(s) -
Lai Ziwei,
Zhang Shuailin,
Zheng Nan,
Yu Shichen,
Ageishi Masaki,
Jinnai Hiroshi,
Cao Yan
Publication year - 2020
Publication title -
journal of applied crystallography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.429
H-Index - 162
ISSN - 1600-5767
DOI - 10.1107/s1600576719014705
Subject(s) - triclinic crystal system , nanostructure , crystallography , materials science , polymer , phase (matter) , symmetry (geometry) , crystal structure , crystal (programming language) , diffraction , nanotechnology , chemistry , composite material , optics , physics , geometry , mathematics , organic chemistry , computer science , programming language
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.