NMR proton relaxation for measuring the relative concentration of nanoparticles in liquids.

The measurement of relative concentration of nanoparticles in liquids has been investigated using NMR proton relaxation, addressing a gap in analytical capabilities for highly concentrated dispersions. This technique has a limited footprint, short measurement time and ease of operation making it a promising quality control method to support the development and manufacture of nanomaterials.

On the use of Raman spectroscopy to characterize mass-produced graphene nanoplatelets.

Raman spectroscopy is one of the most common methods to characterize graphene-related 2D materials, providing information on a wide range of physical and chemical properties. Because of typical sample inhomogeneity, Raman spectra are acquired from several locations across a sample, and analysis is carried out on the averaged spectrum from all locations. This is then used to characterize the "quality" of the graphene produced, in particular the level of exfoliation for top-down manufactured materials.

Rapid monitoring of graphene exfoliation using NMR proton relaxation.

Graphene is now being produced on an industrial scale and there is a pressing need for rapid in-line measurements of particle size for Quality Assurance and Quality Control (QA/QC). Standardised characterisation techniques such as electron microscopy and scanning probe microscopy can be time consuming and may require pre-processing steps and/or solvent elimination prior to measurements. Herein, we demonstrate the use of nuclear magnetic resonance (NMR) proton relaxation as a powerful method for monitoring the sonication assisted liquid phase exfoliation of graphene.

Using nuclear magnetic resonance proton relaxation to probe the surface chemistry of carbon 2D materials.

Nanomaterials exhibit a high surface-area-to-mass ratio, making surface properties key to optimising product performance. However, characterising surfaces at the nanoscale is difficult to achieve, especially as nanomaterials are often in liquid dispersions. Herein, we demonstrate the use of nuclear magnetic resonance proton relaxation for rapid characterisation of the surface chemistry of graphitic materials.

Determining the Level and Location of Functional Groups on Few-Layer Graphene and Their Effect on the Mechanical Properties of Nanocomposites.

Graphene is a highly desirable material for a variety of applications; in the case of nanocomposites, it can be functionalized and added as a nanofiller to alter the ultimate product properties, such as tensile strength. However, often the material properties of the functionalized graphene and the location of any chemical species, attached via different functionalization processes, are not known. Thus, it is not necessarily understood why improvements in product performance are achieved, which hinders the rate of product development.

Terahertz time-domain spectroscopy as a novel metrology tool for liquid-phase exfoliated few-layer graphene.

Few-layer graphene (FLG) platelets exfoliated directly from graphite are finding a wide range of potential applications, including composites and printed electronics. However, characterisation of the FLG material following incorporation into polymers, including the quality of the dispersion, remains a challenge. Here, we present the use of terahertz time-domain spectroscopy as a potential solution to this challenge which could form the basis of a rapid characterisation tool.

Enhancement of Fracture Toughness of Epoxy Nanocomposites by Combining Nanotubes and Nanosheets as Fillers.

In this work the fracture toughness of epoxy resin has been improved through the addition of low loading of single part and hybrid nanofiller materials. Functionalised multi-walled carbon nanotubes (f-MWCNTs) was used as single filler, increased the critical strain energy release rate, G, by 57% compared to the neat epoxy, at only 0.1 wt% filler content.

Highly Conductive Graphene and Polyelectrolyte Multilayer Thin Films Produced From Aqueous Suspension.

Rapid, large-scale exfoliation of graphene in water has expanded its potential for use outside niche applications. This work focuses on utilizing aqueous graphene dispersions to form thin films using layer-by-layer processing, which is an effective method to produce large-area coatings from water-based solutions of polyelectrolytes. When layered with polyethyleneimine, graphene flakes stabilized with cholate are shown to be capable of producing films thinner than 100 nm.

Spectroscopic metrics allow in situ measurement of mean size and thickness of liquid-exfoliated few-layer graphene nanosheets.

Liquid phase exfoliation is a powerful and scalable technique to produce defect-free mono- and few-layer graphene. However, samples are typically polydisperse and control over size and thickness is challenging. Notably, high throughput techniques to measure size and thickness are lacking.

Turbulence-assisted shear exfoliation of graphene using household detergent and a kitchen blender.

To facilitate progression from the lab to commercial applications, it will be necessary to develop simple, scalable methods to produce high quality graphene. Here we demonstrate the production of large quantities of defect-free graphene using a kitchen blender and household detergent. We have characterised the scaling of both graphene concentration and production rate with the mixing parameters: mixing time, initial graphite concentration, rotor speed and liquid volume.

Scalable production of large quantities of defect-free few-layer graphene by shear exfoliation in liquids.

To progress from the laboratory to commercial applications, it will be necessary to develop industrially scalable methods to produce large quantities of defect-free graphene. Here we show that high-shear mixing of graphite in suitable stabilizing liquids results in large-scale exfoliation to give dispersions of graphene nanosheets. X-ray photoelectron spectroscopy and Raman spectroscopy show the exfoliated flakes to be unoxidized and free of basal-plane defects.