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Biography
Previous research (PhD)
My PhD investigated the control over dispersion and interfacial properties of soft matter and carbonaceous systems by manipulating their interactions in situ. Specifically, the work centred on aqueous processing of 2-dimensional carbon materials, graphene oxide and reduced graphene oxide. I investigated methods of controlling their bulk stability and adsorption at interfaces; these materials are a single atom in thickness, but lateral dimensions can be on the order of tens of micrometers. As such, graphene oxides have an enormous surface area with which other molecules can interact, and are therefore excellent candidates for applications such as water purification and oil recovery.
There are however major challenges associated with their use. In the case of water purification, it is necessary to ensure the removal of the carbon materials. In the case of oil recovery, the particles do not adsorb spontaneously at the oil–water interface. I utilised surfactant molecules to aid recovery and emulsification. Depending on choice of surfactant and the resultant interactions with the graphene oxides, I found that it is possible to easily destabilise and recover the carbon materials by minimising their surface charge. Moreover, I could enhance their interfacial activity by synergism with the surfactant molecules. The experiments to unpick the complex relationships between surface chemistry, intermolecular interactions, self-assembly and interfacial thermodynamics for these systems involved a broad combination of experimental techniques, including small-angle scattering measurements, atomic force microscopy and a combination of reflectivity and tensiometry measurements.
In addition, I investigated the self-assembly of a class of zwitterionic surfactants that spontaneously form viscoelastic wormlike micelles in aqueous solution. The work involved a systematic analysis of how their structure and rheology change when exposed to a variety of scientifically (and industrially) relevant additives.
Current research (Postdoc)
Currently I research the role of organic friction modifiers (OFMs) in engines. These are molecular additives that are incorporated into engine oil formulations to reduce friction and wear between contacting machine parts, improving performance and longevity. The precise mechanism by which these compounds adhere to a metal surface and reduce friction is still debated. The classical theory suggests a monolayer of OFM forming a packed brush at the metal interface. However, newer molecular dynamics simulations posit weak adsorption of hemi-spherical micelles. In order to utilise these compounds optimally, this mechanism must be understood. Design of new OFMs will result in significant improvements in the lifetimes of engines and other mechanical devices while greatly reducing emissions.
To address the mode of OFM action, we have developed a custom-made tribometer rig which is a device for measuring friction. The tribometer is specially designed to be mounted in neutron and X-ray beamlines located in facilities in the UK (ISIS Neutron and Muon Source and Diamond Light Source, Didcot) and France (Institut Laue-Langevin, Grenoble). This enables us to monitor the structural behaviour of friction modifiers while the tribometer creates shear stress on the surface. Currently, I have multi-contrast reflectivity profiles showing the ability to selectively monitor the friction modifiers. I have observed structural changes with shear and solvency and am modelling this to enable structural changes to be linked with measured changes in friction. An interesting result is the presence of an unknown hydrogenated material at the metal interface. Through further investigation I have demonstrated that this compound is almost certainly water and has a significant impact on the surface interactions, phase behaviour and structure of the system. Additional applications could include improved materials and compounds for joint lubrication and drag reduction in items such as skis, surf boards and boats, yielding enhanced performance and environmental impact.
Future research (Fellowship)
In 2021 I will begin researching functional surface coatings as part of my Oppenheimer Research Fellowship at the University of Cambridge.