Controlling and Characterizing Complex Fluid-Fluid Interfaces

Controlling and Characterizing Complex Fluid-Fluid Interfaces

Javen S. Weston

Postdoctoral Researcher: Georgetown University Department of Physics and National Institute of Standards and Technology

Research Interests: Material-material interfaces are everywhere around us and understanding how to control and modify them is at the center of many current research problems, from formulating laundry detergents to creating highly efficient photovoltaic solar cells. My research interests primarily revolve around studying how to create, stabilize, and modify these interfaces; with particular interests in surfactant adsorption, emulsion and foam stabilization, nanoparticle dispersions/composites, and nanoparticle assembly at fluid-fluid interfaces. My experience provides me with an excellent foundation for a productive research career by combining experience using a variety of characterization techniques with valuable contacts and collaborators at national labs and industrial R&D departments.

Successful Proposals: Co-wrote an ADNOC-OSC 2-year Research and Development Grant ($460,000) and wrote 8 accepted beam time proposals at three different international scientific user facilities

Postdoctoral Project: “Developing Measurements of Structure-Property Relationships for Complex Fluids in Extreme Environments.”

Under supervision of Steve Hudson (NIST, Mat. Sci. and Eng. Division), Daniel Blair (Georgetown, Dept. of Physics), and Katie Weigandt (NIST, Center for Neutron Research)

PhD Dissertation: “Metal Oxide Nanoparticles: wettability modification for emulsion stabilization and electrostatically induced gelation”

Under supervision of Jeffrey H. Harwell, Chemical Engineering, University of Oklahoma

Research Experience: As a post-doctoral researcher, I have been helping to develop an apparatus using small-angle neutron scattering to simultaneously measure the rheology and structure of complex fluids under extreme flow conditions and elevated temperatures/pressures. The device will eventually be available for use by external users and provide a powerful new tool for investigating flow conditions relevant to pharmaceutical, petroleum, coatings, and polymer processing applications. While developing this device, I have also completed work using neutron scattering to study shear-induced structures in microemulsions and worm-like micelles.

My graduate research was completed as a member of the Center for Interfacial Reaction Engineering with funding from a DoE-EPSCoR Grant. I studied how systematic surface modification alters the wettability of nanoparticles along with their ability to stabilize oil/water emulsions. Additional work studying dispersions of oppositely charged nanoparticles and gels formed by their heteroaggregation was also a part of my dissertation.

My research experiences introduced me to a wide variety of different topics within the realm of colloid and interface science. While an undergraduate, I worked as a research assistant in the Applied Surfactant Lab (ASL), which balanced industrially-sponsored research projects with academic grant-funded research. Over my time in the ASL, I worked on a variety of different projects including: formulating a high performance ‘green’ hard surface cleaner, investigating the competitive adsorption of surfactants and polyelectrolytes on metal oxide nanoparticles, optimizing nanoparticle propagation through porous media, developing ultra-low interfacial tension surfactant blends for use in environmental remediation applications, improving performance of erasable inks, and incorporating polyelectrolytes into detergent formulations.

Teaching Interests: Throughout the course of my graduate and post-graduate work I have had several opportunities to gain hands-on teaching experience. During my first year of graduate school I was given opportunities to act as a guest-lecturer and TA in undergraduate-level laboratory courses. Then, during fall semesters throughout the remainder of my graduate studies, I was asked to act as the Instructor of Record for a section of a First-Year Engineering Experience course in OU’s College of Engineering, for which I was awarded an Outstanding Graduate Assistant Teaching Award. As faculty I would be interested in teaching a wide variety of courses and would be excited to teach any course. Specific interests would include materials, fluid mechanics, thermodynamics, and colloids/surfaces focused courses.

Research Interests: As a faculty member, my research philosophy would rest on the belief that the best way to maintain a well-funded, relevant set of research goals is to strike a balance between basic scientific research and industry-funded research/consulting projects. Combining these two goals can be difficult, but I believe it is the best way to stay up to date with the cutting edge of academic research while simultaneously anticipating industry needs, which are often an excellent indicator of future research directions in engineering fields. I also believe in using a diverse group of researchers in terms of experience levels; using undergraduates, graduate students, and postdoctoral researchers to maximize the productivity of the research group and provide students with leadership and managerial experience. In particular, working with undergraduate researchers from other STEM majors, or creating opportunities for interdepartmental collaboration, can help solve problems far more synergistically than can occur when all the students and faculty involved are approaching the research problem from a similar background.

            My research interests revolve around understanding how micro- and nano-scale interfacial and colloidal forces affect bulk properties of composites, membranes, emulsions, and complex fluids. My proposed research is bound together under the theme of “engineered interfaces” with the goal of being able to generate materials with optimized microstructural and bulk properties for their given application, while generating generalized relationships that can inform future material design. Below, are detailed descriptions of two specific research thrusts:

§  Structure and rheology of complex fluid-fluid interfaces - Solids-stabilized fluid-fluid interfaces are encountered in a variety of industrial and practical environments, such as asphaltene-stabilized emulsions in the oil industry that can plug pipelines and production wells, or delicious protein-stabilized foams like whipped cream and mousse. The bulk properties of these fluids are governed by complex interactions spanning from the nanometer-scale particles to the micron-scale droplets to the bulk fluid properties. Relatively little work has been done to generate systematic relationships that tie the microstructural arrangement of particles and droplets to the bulk properties that are important in industrial applications

§  Engineering nanoscale structure via emulsion polymerization - Membrane separations are becoming increasingly popular in a wide variety of applications such as municipal water desalination, waste water treatment, and pharmaceutical purification processes. Current manufacturing methods for these membranes experience problematic trade-offs between flux and selectivity of the resulting membrane. Using in situ photopolymerization of a bicontinuous microemulsion phase could provide a new way to finely tune the size selectivity of a membrane without greatly diminishing the flux.

My desire would be to supplement these long-term research thrusts with shorter, industry-sponsored projects with more immediate practical and commercial goals, by reaching out to various industry collaborators I have worked with during my research career.

Selected Publications:

·     JS Weston, DS Seeman, DL Blair, PF Salipante, SD Hudson, and KM Weigandt. “A device for simultaneous rheological and microstructural characterization of complex fluids at extreme shear rates,” Soft Matter, Submitted June 2017.

·     JS Weston, JH Harwell, and BP Grady. “Rheological characterization of yield stress gels formed via

electrostatic heteroaggregation of metal oxide nanoparticles,” Soft Matter, Under revision June 2017

·     JS Weston, RE Jentoft, BP Grady, DE Resasco, and JH Harwell. "Silica Nanoparticle Wettability: Characterization and Effects on Emulsion Properties," Industrial & Engineering Chemistry Research, DOI: 10.1021/ie504311p, 2015.

·     JS Weston, D Venkataramani, CP Aichele, BP Grady, JH Harwell, and DE Resasco. “Pseudosolid, Shear-Thinning Gel Formation in Binary Dispersions of Metal Oxide Nanoparticles at Low Volume Fractions,” Langmuir, 30 (49), 14982, 2014.

·     JS Weston, JH Harwell, B-J Shiau, and M Kabir, “Disrupting admicelle formation and preventing surfactant adsorption on metal oxide surfaces using sacrificial polyelectrolytes,” Langmuir, 30 (22), 6384-6388, 2014.

·     N Briggs, JS Weston, B Li, D Venkataramani, CP Aichele, JH Harwell, and S Crossley. “Multiwalled Carbon Nanotubes at the Interface of Pickering Emulsions,” Langmuir, 31, 13077, 2015.