Working with colleagues at the University of Newcastle and beyond, Professor Erica Wanless is leading two projects exploring how particle coatings change behaviours at phase boundaries.
Colloid chemistry is a form of materials science particularly concentrating on mixtures, where particles of one or more insoluble material are suspended within a dispersion medium.
Surface chemistry is closely linked to colloid chemistry due to a focus on how the surfaces of these particles affect the physical and chemical interactions between the particles and the medium in which they are dispersed.
The science of surfaces and particles is essential to food technology, the creation of personal care and cleaning products products, as well as the enhancement of biomedical and industrial technologies.
Erica and her team are expert in designing and testing surface modifications to particles, as well as measuring the behaviours of particles at the phase boundary in new and existing colloidal dispersions.
HAIRY POLYMER FILMS
Erica is leading an Australian Research Council funded team in exploring the next generation of polymer particle films, or coatings.
These hairy polymer films are added to surfaces or particles to invoke changes to the material's properties, such as wettability, friction and adhesion, at the phase boundary.
"This project is looking at coating solid surfaces that change depending on what is in the aqueous environment, whether it is salt, whether it is a change of pH or change of temperature," Erica explains.
"Although what we are doing is at a very fundamental level, there are a lot of applications where they could be added into an existing technology."
Erica cites industrial applications, such as inclusion in paints, and biomedical applications, such as coating implants, as examples of possible use.
"We are working with water-based systems but we could conceivably do that in an oil environment, or other sort of environment as well," Erica suggests.
"We can now grow polymer from the surface of solid particles to make a hairy particle. Or we can make a hairy flat surface."
"The idea of using the hairs to open and close a hole in a membrane is something that we have talked about exploring in the future."
STABILISING FLUID INTERFACES
In a second major project, Erica is conducting investigations into how polymeric colloids and mineral particles can stabilise fluid interfaces in particle-stabilised foams or emulsions.
In minerals processing, interfacial stability is essential to the process of using air bubbles to separate valuable material from waste. Other applications for foams include personal care and food products.
Emulsions are a two-phase system involving the dispersion of liquid particles within a liquid medium. Emulsions occur in food, cosmetic, and personal care products.
Again with funding from the Australian Research Council, Erica and her team are looking at ways to stabilise both air bubbles, and oil droplets, when they are surrounded by water.
"In a product that you would buy, say mayonnaise, coalescence would be what appears as uninviting phase separation in the container," Erica states.
"In this project we are working to coat droplets with colloidal particles, to try and prevent them from coalescing."
"Using high speed video, we are examining the coalescence process so we might understand how to employ colloidal particle coatings to make these interphase systems more or less stable depending on their application."
TEACHING AND TEAMS
It was in the third year of her own undergraduate studies that Erica discovered her interest colloid and surface chemistry.
"I enjoyed both maths and chemistry and discovered that physical chemistry would utilise both of those skills, and that was it," Erica recalls.
After two years of postdoctoral work in New Zealand, Erica applied for a lecturing position at Newcastle.
Surprisingly perhaps, Erica's favourite collaborators are her students.
"Setting students on their career paths, making sure they focus on research that is high profile enough to open doors, and seeing them grow through the long, deep PhD process is the most rewarding thing," Erica affirms.
"What we publish seems to be read by lots of people and gets lots of citations, so if students are co-authoring those publications, that is their ticket to whatever career they want to get."
Her students have a high success rate gaining employment, in areas as diverse as mining, explosives, paint, food technology and in universities.
Regardless of their chosen focus, Erica ensures her students receive superior applied training, including lessons in the effectiveness of team-based research.
"My students know that science is collaborative. You sit around with the supervisor, colleagues and other students and analyse the data," she continues.
"No matter what stage of your career you are at, working in a team is much more powerful than trying to do it yourself in a corner of the lab."
Erica values highly her own international network of collaborators.
"If each collaborator has a different skills base and you can complement each other, you might see something from a data set and they might see something additional," Erica says.
"So it is much more powerful to have another set of eyes and another mind."
Erica has strong collaborative connections with researchers at the Universities of Sheffield and Manchester in the UK, Osaka Institute of Technology in Japan and the Technical University of Berlin, Germany, as well as the University of New South Wales in Australia.
At the University of Newcastle, Erica often works with researchers from Chemical Engineering, particularly Dr Grant Webber.
"We are very open to working with other researchers, and that works quite well for short-term international visitors who come and access some of the more unique equipment or expertise that we have here," Erica advises.
A trailblazer in the use of soft-contact atomic force microscopic imaging, specifically within water, Erica is recognised as an international leader in her field.
Erica and her team are equally sought after for their skill in the use of other surface or particle measurement techniques including ellipsometry, quartz crystal microbalance, and microelectrophoresis.
"We are not really in the business of making new materials per se," Erica says.
"But when other people do, and then they want measurements, they come to us. Because that is our business."
WOMEN IN STEM
Erica is a co-founder of HunterWiSE, a group dedicated to promoting and supporting girls and women in STEM.
HunterWiSE features two interlinked actions aimed at increasing the number of girls and women participating in STEM through a school program and a series of networking events across the Hunter for women STEM professionals.
This approach is designed to steer women toward STEM, and encourage their retention in the STEM pipeline.