Viscoelastic Covalent Organic Nanotube Fabric via Macroscopic Entanglement

Abstract

Covalent organic nanotubes (CONTs) are one-dimensional porous frameworks constructed from organic building blocks via dynamic covalent chemistry. CONTs are synthesized as insoluble powder that restricts their potential applications. The judicious selection of 2,2′-bipyridine-5,5′-dicarbaldehyde and tetraaminotriptycene as building blocks for TAT-BPy CONTs has led to constructing flexible yet robust and self-standing fabric up to 3 μm thickness. The TAT-BPy CONTs and TAT-BPy CONT fabric have been characterized by solid-state one-dimensional (1D) 13C CP-MAS, two-dimensional (2D) 13C–1H correlation NMR, 2D 1H–1H DQ–SQ NMR, and 2D 14N–1H correlation NMR spectroscopy. The mechanism of fabric formation has been established by using high-resolution transmission electron microscopy and scanning electron microscopy techniques. The as-synthesized viscoelastic TAT-BPy CONT fabric exhibits high mechanical strength with a reduced modulus (E r) of 8 (±3) GPa and hardness (H) of 0.6 (±0.3) GPa. Interestingly, the viscoelastic fabric shows time-dependent elastic depth recovery up to 50–70%.

Structural and Morphological Transformations of Covalent Organic Nanotubes

“…In previously reported CONT‐1, 1D NMR spectra, including CPMAS and HPDEC NMR, indicate the formation of NH‐imidazole‐linked defects and polymers as side products along with imine‐linked one‐dimensional CONTs (Figure 1a). [1a] The formation of NH‐imidazole was further suppressed in TAT‐BPy CONTs using careful screening via advanced solid‐state NMR techniques like 2D 1 H‐ 13 C correlation, 1 H‐ 1 H single quantum‐ double quantum (SQ‐DQ) and 1 H‐ 14 N correlation NMR along with 1D CPMAS NMR [1b] . However, new characteristic peaks in solid‐state 1 H and 2D solid‐state NMR for CONT‐1 suggested the possible rearrangement of bis‐imine to N‐methyleneimidazole.…”

Monolayer-Assisted Surface-Initiated Schiff-Base-Mediated Aldol Polycondensation for the Synthesis of Crystalline sp2 Carbon-Conjugated Covalent Organic Framework Thin Films

“…The reduced modulus (E) and hardness (H) were extracted from the P−h curves by Oliver and Pharr analysis, which demonstrate that both the TFPT−TMT (E = 25.5 ± 2.2 GPa, H = 1.2 ± 0.1 GPa) and TB−TMT films (E = 19.0 ± 0.8 GPa, H = 0.9 ± 0.1 GPa) are substantially stiffer and harder than imine-based COF films fabricated via spin coating (E = ∼8 GPa, H = ∼0.6 GPa) or liquid−liquid interfacial methods (E = ∼15.3 GPa, H = ∼66 MPa) (Figure S10). 41,42 Such excellent mechanical behavior could be explained by the high-quality film with fewer defects and robust framework caused by vinylene linkages. 43 The morphology of the sp 2 c-COF films was analyzed by scanning electron microscope (SEM) and high-resolution transmission electron microscope (HR-TEM) measurements.…”

Novel Capturer-Catalyst Microreactor System with a Polypyrrole/Metal Nanoparticle Composite Incorporated in the Porous Honeycomb-Patterned Film

“…Self-templated synthesis allows precise control over the final product's size, shape, and morphology and a high degree of pore uniformity. 4 However, the endeavor of choosing the right template is critical, and it can be challenging to find suitable templates for some desired structures. 5 Moreover, it is difficult to remove the template without damaging the final structure, and traces of residue may remain, affecting the final material's properties.…”

“…One of the versatile approaches used to create various nanostructures and porous materials is self-templated synthesis, also known as template-assisted or template-directed synthesis. , In this process, the template serves as a scaffold, guiding the formation of the final structure. Self-templated synthesis allows precise control over the final product’s size, shape, and morphology and a high degree of pore uniformity . However, the endeavor of choosing the right template is critical, and it can be challenging to find suitable templates for some desired structures .…”