(4gc) Molecular Engineering of Sustainable Foams and Bubbly Fluids

Foams and bubbly liquids formed by the entrapment of air bubbles in a continuous liquid phase affect food, beverage, environment, and numerous industrial processes. Additives, including surfactants, polymers, proteins, particles, and droplets, influence the equilibrium and dynamics of these bubbly colloids. My research interests lie in molecular and macromolecular engineering of more efficient, sustainable, and eco-friendly surface-active additives than the widely used detergents, fluorinated compounds, and petroleum-derived products. My research will focus on the impact of physicochemical properties of the additives on stability, rheology, and applications of foams and bubbly colloids.

My postdoctoral research at Stanford University focused on the effect of antifoam droplets on bubbles in aerated lubricating oil. Small air bubbles are generated and entrapped in the liquid bulk phase, which can aerate lubricating oils, causing degradation of the lubricant performance and potentially damaging the lubricated machinery. Silicon-based antifoam additives commonly added to lubricating oil to destabilize foams, also hinder the release of air from the aerated lubricating oil. However, a mechanistic understanding of how antifoam additives stabilize air bubbles in the bulk lubricating oil was a longstanding challenge. We explored the question using a combination of theory and experiments. We tracked individual bubbles freely rising in a column of lubricating oil with systematically increased antifoam additive concentration and developed a theoretical model to capture the role played by hydrodynamics and interfacial properties of additives.

My doctorate research focused on drainage via stratification in ultrathin micellar foam films. Ultrathin foam films of soft matter exhibit stratification due to confinement-induced structuring and layering of supramolecular structures like micelles or micelle-polymer complexes. The interplay of local capillary and disjoining pressure leads to the formation and growth of non-flat nanoscopic structures on stratifying foam films. We developed and utilized IDIOM (interferometry digital imaging optical microscopy) protocols to analyze the shape and size evolution of these nanoscopic structures. Using thin film equation amended with oscillatory disjoining pressure, we developed a theoretical model to capture the shape evolution, advancing the understanding of the dynamics of stratification and the role of surface forces. We discovered similar stratification can arise in polymer-surfactant mixtures.

I plan to establish an experimental research group to study the stability and dynamics of colloidal soft matter formulation containing sustainable ingredients. We will focus on advancing the understanding of foamability, foam stability, interfacial properties, and self-assembly of sustainable and eco-friendly materials like plant-based biosurfactants.

Teaching Interest:

I had the opportunity to mentor many undergraduate and graduate students during my doctorate research. I have been the teaching assistants in multiple undergraduate and graduate courses, including advanced transport phenomena and microhydrodynamics.

I obtained my Bachelor, master and doctoral degrees in the major of Chemical Engineering, so that I am comfortable to teach core fundamental courses in Chemical Engineering major, especially transport phenomena. Based on my research experience, I’d like to teach advanced coursed on mircohydrodynamics, capillarity, colloidal and interfacial science, intermolecular and surface forces.