Dey, Kaushik ; Bhunia, Surojit ; Sasmal, Himadri Sekhar ; Reddy, C. Malla ; Banerjee, Rahul (2021) Self-Assembly-Driven Nanomechanics in Porous Covalent Organic Framework Thin Films Journal of the American Chemical Society, 143 (2). pp. 955-963. ISSN 0002-7863
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Official URL: http://doi.org/10.1021/jacs.0c11122
Related URL: http://dx.doi.org/10.1021/jacs.0c11122
Abstract
Nanomechanics signifies a key tool to interpret the macroscopic mechanical properties of a porous solid in the context of molecular-level structure. However, establishing such a correlation has proved to be significantly challenging in porous covalent organic frameworks (COFs). Structural defects or packing faults within the porous matrix, poor understanding of the crystalline assembly, and surface roughness are critical factors that contribute to this difficulty. In this regard, we have fabricated two distinct types of COF thin films by controlling the internal order and self-assembly of the same building blocks. Interestingly, the defect density and the nature of supramolecular interactions played a significant role in determining the corresponding thin films’ stress–strain behavior. Thin films assembled from nanofibers (∼1–2 μm) underwent large deformation on the application of small external stress (Tp–Azofiber film: E ≈ 1.46 GPa; H ≈ 23 MPa) due to weak internal forces. On the other hand, thin films threaded with nanospheres (∼600 nm) exhibit a much stiffer and harder mechanical response (Tp–Azosphere film: E ≈ 15.3 GPa; H ≈ 66 MPa) due to strong covalent interactions and higher crystallinity. These porous COF films further exhibited a significant elastic recovery (∼80%), ideal for applications dealing with shock-resistant materials. This work provides in-depth insight into the fabrication of industrially relevant crystalline porous thin films and membranes by addressing the previously unanswered questions about the mechanical constraints in COFs.
Item Type: | Article |
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Source: | Copyright of this article belongs to American Chemical Society. |
Keywords: | Covalent Organic Frameworks; Thin Films; Nanospheres; Fibers; Defects. |
ID Code: | 115683 |
Deposited On: | 16 Mar 2021 06:06 |
Last Modified: | 16 Mar 2021 06:06 |
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