The scientific goal of this project is to explore the effect of heterogeneous surface functionality on emulsion formation and stability using Janus particles with well-defined surface compositions. Emulsions are ubiquitous in industrial processes, ranging from cosmetics to petrochemicals, and the fundamental understanding of emulsion behavior has been the subject of over a century of research. Traditional emulsification processes apply molecular amphiphiles to stabilize the oil-water interface. Similarly, homogenous particles are capable of adsorbing to oil-water interfaces to stabilize emulsion droplets. Yet in many industrial and natural systems, the adsorbing particles are not homogenous in shape or surface chemistry, and, while a number of theoretical studies have predicted the behavior of surface anisotropic particles, few experiments have been conducted to quantify the influence of heterogeneities on the interface.
The research is carried out in three parallel steps. First, the coalescence of emulsions is examined, using both homogenous and heterogeneous particles. Second, interfacial structure and rheology of surfaces stabilized by homogeneous particles is probed, focusing on the quantification of interfacial properties as a function of particle size and concentration. And third, interfacial structure and rheology of surfaces stabilized by Janus particles are probed, focusing on the role of interfacial order in the mechanics of the surface. Taken together, these studies allow us to understand fundamental aspects of the effect of surface heterogeneities on emulsion stability and engineer optimized systems for stabilizing multiphase systems.
Intellectual Merit: A major goal of the research is to advance the understanding of the effect of spatially heterogenous surface chemistry of micron-sized particles on emulsion stabilization. The results of this project are likely to impact a wide range of industries, including crude oil exploration and separation processes, water purification, and next-generation pharmaceutical/personal care products. The PIs have research experience in asymmetric particle surface modification, emulsion preparation, and characterization of interfacial properties. Further, the PIs have access to (i) surface characterization instruments such as scanning electron and atomic force microscopy, (ii) emulsion, rheology, and stability equipment, and (iii) surface visualization tools.
Broader Impacts: The importance of emulsions and emulsion-based processes in industry cannot be overstated. A range of students from the high school to the graduate level are trained in both the fundamental and the applied aspects of emulsion technology. Moreover, an international component enables the training of CCNY students locally and abroad (Colombia, England, and Sweden). CCNY students typically come from a diverse background, and the PIs have a long history of training a cadre of students with wide ranging backgrounds. CCNY is a recognized minority serving institution, which serves a diverse undergraduate student body of Hispanic (36%), African American (30%), Asian (23%), and White (11%) students. Further, individual mentoring will provide female and minority students with a mentoring network early on in their careers. Research findings will be broadly disseminated using journal publications, conferences, and websites and will be used to develop hands-on experiences for high school and undergraduate students.
