Date/Time: 04-23-2019 - Tuesday - 05:00 PM - 07:00 PM
Justin Hendrix1

1, Naval Surface Warfare Center, Dahlgren Division, Dahlgren, Virginia, United States

Carbon Nanotubes (CNTs) and Metal Organic Frameworks (MOFs) represent two of the most promising classes of emerging materials in engineering today. Together, they exhibit many useful properties such as high conductivity [1], catalytic reactivity [3], porosity [4], and strength [2]. Methods in integrating these materials towards electromagnetic and chemical applications is of strategic importance for defense. Innovative materials have often been designed by combining low and high dimension constituents, through compositing, as a means to improving the functionality. In this work, we were able to combine these nanomaterials by synthesizing novel MOF-CNT nanostructured composites, using zirconium containing MOF (MOF-808).
MOF-808 is composed of zirconium (IV) nodules, connected by organic carboxyl linkers, to create a nanoporous octahedral 3D crystal structure. Carboxylated functional groups are believed to be an important surface modification, due to its ability to bridge the zirconium nodules. Multiwalled CNTs, surface functionalized with carboxyl end groups, were used as the reinforcing agent with MOF-808 to create a MOF-CNT composite. The functionalities were chosen to create a MOF-CNT composite, linked by primary bonds.
Scanning transmission electron microscopy (STEM) and nanoarea electron diffraction are powerful techniques in identifying structural changes at atomic scale resolution. Using a NION UltraSTEM-200X and a JEOL 2200FS at the U.S Naval Research Laboratory, we are able to identify MOF-808 adhesion to the surfaces of functionalized CNTs. Analysis shows the existence of lattice defects at the interface of MOF-808, as synthesized with carboxylated CNTs. The disruption is believed to be caused by the carboxylated CNTs acting as heterogeneous nucleation sites, forming the MOFs around the nanotube center. In this work, STEM and electron diffraction are used as effective techniques to study the interface of surface modified nanostructure composites.

[1] V. Trovato et al., "Carbon nanotubes textile coating for the development of wearable sensors," 2018 7th International Conference on Modern Circuits and Systems Technologies (MOCAST), Thessaloniki, 2018, pp. 1-4.
doi: 10.1109/MOCAST.2018.8376600
[2] Ho, Po-Hsun, et al. "Intrinsically ultrastrong light-matter interactions in crystalline films of carbon nanotubes." arXiv preprint arXiv:1803.01087 (2018).
[3] Brønsted Basicity in Metal–Organic Framework-808 and Its Application in Base-Free Catalysis Xiaodan Yan, Kai Wang, Xiaocheng Xu, Shuhua Wang, Qian Ning, Weiming Xiao, Ning Zhang, Zijuan Chen, and Chao Chen Inorganic Chemistry 2018 57 (14), 8033-8036 DOI: 10.1021/acs.inorgchem.8b01044
[4] Farha OK, Özgür Yazaydõn A, Eryazici I, Malliakas CD, Hauser BG, Kanatzidis MG, Nguyen ST, Snurr RQ, Hupp JT: De novo synthesis of a metal–organic framework material featuring ultrahigh surface area and gas storage capacities. Nat. Chem. 2010, 2:944–948.

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