Research ArticleMATERIALS SCIENCE

Dynamics and healing behavior of metallosupramolecular polymers

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Science Advances  28 Apr 2021:
Vol. 7, no. 18, eabe4154
DOI: 10.1126/sciadv.abe4154
  • Fig. 1 The healing process in polymers.

    (A) The final stages of the healing process in polymers involve wetting, interdiffusion with reentanglement, and randomization. (B) To investigate the healing process on a length scale of a few nanometers, metallosupramolecular polymers (MSPs) assembled from telechelic PEB with terminal Mebip ligands (Mn = 3800 g mol−1; m ≈ 0.32, n ≈ 0.68, p ≈ 55) and either Eu(ClO4)3 or Tb(ClO4)3 were studied. The two metallosupramolecular polymers display similar properties, but the different ion types can be monitored in a spatially resolved manner.

  • Fig. 2 Healing of EuBKB.

    (A to C) Plots of the healing efficiency at 80°C as a function of healing time based on the recovery of (A) tensile strength, (B) strain at break, and (C) toughness. (D) Plot of the stress intensity factor K1 of EuBKB determined via fracture mechanics experiments as a function of healing time. (E) Photographs showing the propagating crack tip during the fracture of a notched EuBKB film in the (i) pristine state, (ii) after healing a severed sample for 5 min, and (iii) after complete healing (10 min). (F) Comparison of the tensile strength–based healing efficiency as a function of healing time (t0.25) determined from tensile tests as well as fracture mechanics experiments. The dashed lines serve as a guide to the eye.

  • Fig. 3 Healing experiments involving the formation of a mixed EuBKB/TbBKB interphase.

    (A to C) Plots of the mechanical properties of welded EuBKB/TbBKB samples as a function of healing time at 80°C based on (A) tensile strength, (B) strain at break, and (C) toughness, as well as a comparison with the properties of pristine samples. The maximum values are reached after ca. 60 min. Since no reference values can be established for such mixed joints, the absolute mechanical properties are monitored in lieu of a healing efficiency. (D) Plot of the tensile strength as a function of welding time (t0.25) as determined from tensile tests. The dashed line serves as a guide to the eye. (E) Fluorescence microscopy image of the interface of a healed EuBKB/TbBKB film. The luminescence of the different lanthanoid ions complexed with Mebip ligands renders the EuBKB fraction appearing red and the TbBKB fraction appearing bluish/green when placed under ultraviolet (UV) light illumination (λex = 365 nm). (F) Photograph showing the crack tip of a notched EuBKB/TbBKB sample during deformation under UV light illumination (healing time = 120 min and λex = 365 nm). The deviation of the propagating crack from the original interface corroborates complete healing.

  • Fig. 4 Visualization of the interphase.

    STEM coupled with EDX was used to study the interphase of samples obtained after welding EuBKB and TbBKB films together for different amounts of time. (A) Representative EDX elemental maps of Eu (red) and Tb (blue) across the original interface. (B) Representative individual EDX line scans of the intensity of Eu-L and Tb-L lines (open symbols) across the interface and the sigmoidal logistics fit (solid line) after healing times of 5, 20, 40, 60, and 120 min (top to bottom). a.u., arbitrary units.

Supplementary Materials

  • Supplementary Materials

    Dynamics and healing behavior of metallosupramolecular polymers

    Laura N. Neumann, Emad Oveisi, Albrecht Petzold, Robert Style, Thomas Thurn-Albrecht, Christoph Weder, Stephen Schrettl

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    The PDF file includes:

    • Materials Characterization
    • Figs. S1 to S35
    • Tables S1 to S5
    • Legend for movie S1
    • Legend for data file S1

    Other Supplementary Material for this manuscript includes the following:

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