Thin Film Mechano-Energy Induced Slicing of Carbon Nanotubes under Flow

Abstract

Controlling the length of CNTs is important for their applications. As-prepared CNTs are typically nonuniform in length and are entangled, but for applications in electronics and biomedical research in particular, specific lengths are desirable; this has attracted intensified research efforts. We have developed a versatile thin film microfluidic method, which is high in green chemistry metrics, for controlled disentangling and slicing both single-walled CNTs and multiwalled CNTs. The method uses the mechanoenergy generated in a biphasic immiscible mixture of water and o-xylene in a titled vortex fluidic device (VFD) operating at ambient temperature, without the need for using surfactants or other axillary reagents and without the need for applying external fields. Importantly, this simple method can achieve a yield of 93% under continuous flow conditions. The high shear in the dynamic thin film in the VFD is also effective for such processing under continuous flow conditions, such that the method is scalable.

Vortex fluidic induced mass transfer across immiscible phases

“…VFD processing of immiscible liquids can result in well-defined separated phases rather than emulsions, 19 as in (i) biodiesel synthesis (three separate phases), 20,21 (ii) protein separation in a mixture of PEG and aqueous potassium phosphate 22 with no evidence of damage to the proteins under periodic high shear in the topological fluid flows which is in accord with the ability to use the VFD to refold proteins into their native states and to accelerate enzymatic rections, 20 (iii) where water seemingly acts as an ‘anti-solvent’ for a toluene solution of fullerene C 60 in forming self-assembled C 60 nano-tubules, 23 (iv) surface tension induced slicing of single and multiwalled carbon nano-tubes 24 and (v) scrolling of graphene directly from graphite. 25 Spatially controlled energy delivery in the topological fluid flows create conditions for controlling chemistry, which relates to fundamental insights into enhancing catalytic activity in general.…”

Coiling of Single-Walled Carbon Nanotubes via Selective Topological Fluid Flow: Implications for Sensors

“…200 μm in thickness, which, in conjunction with gravitational and centrifugal forces, Faraday waves, and Coriolis forces, produces a unique topological fluid flow behavior that gives the ability to control the formation of non-equilibrium systems in mono- and biphasic systems. , The self-assembly of fullerene C 60 , the scrolling and unscrolling of graphene oxide, and other nanomaterial syntheses have been used to mold the high-shear fluid flow in the device, thereby establishing three different types of submicron topological fluid flows, Figure : , (i) Coriolis force generating a spinning top (typhoon-like) flow from the hemispherical base of the tube, (ii) a double-helical fluid flow arising from the eddies associated with Faraday waves in combination with the Coriolis force from the curved surface along the tube, and (iii) a “spicular” or spherical fluid flow arising from the interplay of the spinning top and double-helical flows of similar diameter. The VFD has multiple applications in chemistry, biotechnology, , food science, and materials processing, , including the formation of SWCNT toroids and slicing CNTs with the processing perturbing their magnetic/chiral properties. − The outcomes of this processing as such in the VFD are consistent with the presence of the aforementioned different topological fluid flows, which depend on the tilt angle of the tube which is optimal at θ = +45° for all applications of the device, the rotational speed, ω, the flow rate through the device when scaling up beyond the so-called confined mode where a specific volume of liquid is housed in the rapidly rotating tube, and the temperature, concentrations, and properties of the liquid or mixtures of liquids …”

Eco-friendly synthesis of carbon nanotubes and their cancer theranostic applications

“…6d). 161 The surface area, retention time, fibre dimensions, (bio)persistency, and reactivity/inherent toxicity can affect the pathogenicity, biocompatibility, and toxicity of CNTs. 162 In the context of medical and biomedical use, precise cellular analyses and specific histopathological assessments need to be performed to evaluate the biocompatibility and pathogenicity of these nanostructures; 112 though the chemically-functionalized CNTs displayed low toxicity, the possible scepticism due to non-biodegradability should be considered.…”