Research ArticleMATERIALS SCIENCE

Near–atomic-scale observation of grain boundaries in a layer-stacked two-dimensional polymer

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Science Advances  14 Aug 2020:
Vol. 6, no. 33, eabb5976
DOI: 10.1126/sciadv.abb5976
  • Fig. 1 Synthesis, electron diffraction, and micromorphology of L-2D-PI.

    (A) Schematic of the surfactant-assisted synthesis of L-2D-PI at an air-water interface. (B) Reaction scheme of Schiff-base condensation between TAPP and DhTPA (blue: C; purple: N; red: O; gray: H). (C) Scanning electron microscopy (SEM) image of the freestanding L-2D-PI thin film transferred onto a hexagonal copper mesh. (D) Selected-area electron diffraction (SAED) pattern. (E) Stitched TEM image. Inset: Fast Fourier transform (FFT) pattern of (E). Scale bar: 0.2 nm−1. The color-coded Fourier mask is overlaid. (F) Color-coded grain orientation map of (E) displaying “micro-flowers.” The triangular-shaped single-crystalline grains (“petals”) emanate from specific locations (“pistils”).

  • Fig. 2 AC-HRTEM imaging of L-2D-PI.

    (A) Unprocessed AC-HRTEM image of L-2D-PI. (B) FFT pattern of (A). The half-circle marks the spatial frequency of 4 nm−1 (i.e., 2.5 Å). The small circles mark the reflections at Nyquist frequency 4.35 nm−1 (i.e., 2.3 Å). (C) Magnified image of (A). (D) Simulated image (thickness: 40 nm; defocus: −100 nm) with the atomic model overlaid.

  • Fig. 3 APBs visualized by AC-HRTEM imaging.

    (A) APB. (B) Schematic of the APB. The arrow indicates the displacement vector R. (C) APB bounded with partial dislocations. The arrows indicate the Burgers vectors, and the partial dislocations are marked by . (D) Schematic of APB formation via two nonlinear partial dislocations. The red and blue spheres represent TAPP and DhTPA units, respectively. Scale bars: 10 nm.

  • Fig. 4 LAGB and HAGB visualized by AC-HRTEM imaging.

    (A) LAGB with a misorientation of 10°. (B) HAGB with a misorientation of 28°. The red and blue arrows mark TAPP and DhTPA terminations, respectively. (C) HAGB with a misorientation of 45°. (D) DFTB models of n-membered rings formed by boundary reconstruction and the relative formation energy per inter-grain DhTPA. The red arrows mark the inter-grain DhTPAs. Scale bars: 10 nm.

  • Fig. 5 Micro-indentation of L-2D-PI.

    (A) Schematic of micro-indentation. (B) SEM image of the L-2D-PI thin film. The micromanipulator of the focused ion beam system is placed right above the film. (C) After pressing the film with the micromanipulator, the film tears along GBs.

Supplementary Materials

  • Supplementary Materials

    Near–atomic-scale observation of grain boundaries in a layer-stacked two-dimensional polymer

    Haoyuan Qi, Hafeesudeen Sahabudeen, Baokun Liang, Miroslav Položij, Matthew A. Addicoat, Tatiana E. Gorelik, Mike Hambsch, Manuel Mundszinger, SangWook Park, Bettina V. Lotsch, Stefan C. B. Mannsfeld, Zhikun Zheng, Renhao Dong, Thomas Heine, Xinliang Feng, Ute Kaiser

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