Dr Christopher S. Roberts

Said SA, Roberts CS, Lee JK, Shaffer MSP, Williams CKet al., 2021, Direct organometallic synthesis of carboxylate intercalated layered zinc hydroxides for fully exfoliated functional nanosheets, Advanced Functional Materials, Vol: 31, Pages: 1-11, ISSN: 1616-301X

Intercalation of organic anions into 2D materials can enable exfoliation, improve dispersion stability, increase surface area, and provide useful functional groups. In layered metal hydroxides, intercalation of bulk structures is commonly achieved by cumbersome and typically incomplete anion exchange reactions. In contrast, here, a series of carboxylate-intercalated layered zinc hydroxides (LZH-R) are synthesized directly, at room temperature, by reacting an organozinc reagent with a precise sub-stoichiometric quantity of the desired carboxylic acid and water. A range of carboxylic acids are used to make new LZH-R materials which are crystalline, soluble, and functionalized, as established by X-ray diffraction, spectroscopic, and microscopy techniques. When R is an alkyl ether carboxylate, this direct synthesis method results in the spontaneous exfoliation of the LZH-R into monolayer nanosheets with high yields (70–80%) and high solubilities in alcohols and water of up to 180 mg mL−1. By altering the carboxylate ligand, functional groups suitable for post-synthetic modification or for detection by fluorescence are also introduced. These examples demonstrate a versatile synthetic route for functional exfoliated nanosheets.

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Baragau I-A, Power NP, Morgan DJ, Lobo RA, Roberts CS, Titirici M-M, Middelkoop V, Diaz A, Dunn S, Kellici Set al., 2021, Efficient Continuous Hydrothermal Flow Synthesis of Carbon Quantum Dots from a Targeted Biomass Precursor for On-Off Metal Ions Nanosensing, ACS SUSTAINABLE CHEMISTRY & ENGINEERING, Vol: 9, Pages: 2559-2569, ISSN: 2168-0485

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Baragau I-A, Power NP, Morgan DJ, Heil T, Lobo RA, Roberts CS, Titirici M-M, Dunn S, Kellici Set al., 2020, Continuous hydrothermal flow synthesis of blue-luminescent, excitation-independent nitrogen-doped carbon quantum dots as nanosensors, JOURNAL OF MATERIALS CHEMISTRY A, Vol: 8, Pages: 3270-3279, ISSN: 2050-7488

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• Citations: 35

Clancy AJ, anthony D, Fisher S, Leese H, Roberts C, Shaffer Met al., 2017, Reductive dissolution of supergrowth carbon nanotubes for tougher nanocomposites by reactive coagulation spinning, Nanoscale, Vol: 9, Pages: 8764-8773, ISSN: 2040-3372

Long single-walled carbon nanotubes, with lengths >10 μm, can be spontaneously dissolved by stirring in a sodium naphthalide N,N-dimethylacetamide solution, yielding solutions of individualised nanotubide ions at concentrations up to 0.74 mg mL−1. This process was directly compared to ultrasonication and found to be less damaging while maintaining greater intrinsic length, with increased individualisation, yield, and concentration. Nanotubide solutions were spun into fibres using a new reactive coagulation process, which covalently grafts a poly(vinyl chloride) matrix to the nanotubes directly at the point of fibre formation. The grafting process insulated the nanotubes electrically, significantly enhancing the dielectric constant to 340% of the bulk polymer. For comparison, samples were prepared using both Supergrowth nanotubes and conventional shorter commercial single-walled carbon nanotubes. The resulting nanocomposites showed similar, high loadings (ca. 20 wt%), but the fibres formed with Supergrowth nanotubes showed significantly greater failure strain (up to ∼25%), and hence more than double the toughness (30.8 MJ m−3), compared to composites containing typical ∼1 μm SWCNTs.

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