Research Case Study - Engineering & Control of Surfactant-laden Flows
Over the past two decades, the use of surfactants as wetting agents has enjoyed considerable attention due to their importance in a variety of industrial and biomedical applications (coating flows, detergency, enhanced-oil-recovery and treatment of respiratory distress syndrome to name a few).
Despite research progress in this area, numerous fundamental problems remain unsolved, as no single approach (experimental, simulations or theory) is able to probe the formidable complexities of the fluid-solid behaviour of amphiphilic molecules (molecules which possess both water-soluble and water-insoluble properties).
The work undertaken collaboratively by multiple teams aims to provide detailed understanding of how surfactants behave at contact lines and adsorb at interfaces, and how this ultimately affects the spreading and wetting of hydrophobic surfaces. In this context, even trivial-sounding problems are not fundamentally understood: How does the surfactant distribution equilibrate and the stresses induced by it balance with the forces at the contact line? How are the latter influenced by surfactant solubility, and the formation of surfactant aggregates at high surfactant concentrations?
These questions underlie striking and technologically important, yet poorly understood effects, such as superspreading (whereby aqueous droplets containing superspreader surfactants spread rapidly to produce perfect wetting over hydrophobic substrates).
This project tackles the fundamental problems mentioned above in a collaborative, systematic, multi-disciplinary and multi-scale manner. The chemistry and molecular interactions require detailed modelling on the molecular level; this must then be scaled up to the lengthscale of droplets and the application itself.
The problem requires new physicochemical understanding of the phenomena and the developed models must be validated, and indeed informed by, detailed and careful experiments.
The deep knowledge of surfactant-laden flows that will be achieved via this transformative research will be used not only to provide accurate and reliable predictions of these flows but also to rationally-design bespoke surfactant molecular architectures for various applications ranging from agrochemicals to enhanced-oil-recovery.