Interfacial Colloid Jamming: From Fundamentals to Applications

Seminar series
Physical Chemistry Seminar
Mon, Dec 2 4:00pm
2033 Young Hall
Speaker Professor Ali Mohraz
University of California, Irvine
Dept. of Chemical Engineering and Materials Science

Abstract: Particle sequestration at the interface of immiscible fluids has been known for decades and exploited in the formulation of solid-stabilized (Pickering) emulsions for drug delivery, oil recovery, food, and personal care products, to name a few.  More recently, new classes of multi-phase mixtures have emerged that exploit interfacial colloid jamming, bridging, ordering, and aggregation for the assembly of higher-order structures from colloidal building blocks. Such mixtures can exhibit rich and highly complex rheology over a wide range of compositions.  In addition, the multiphase nature of these systems makes them excellent templates for the synthesis of bulk composite materials with tunable morphology at the nano- to micrometer scales.  In this talk, our recent efforts to better understand the microstructure and rheology of this new class of soft materials and utilize them for the synthesis of functional composites will be presented with two different examples.  Both systems involve particle assembly at fluid interfaces leading to a fluid-to-gel transition, but through fundamentally distinct mechanisms.  The microstructural origins of gel-like rheology in these mixtures are investigated by quantitative confocal microscopy and bulk rheometry, and will be discussed and compared to traditional systems in which attractive interparticle interactions are a requirement for gelation.  Finally, examples of composite materials derived from these systems will be presented, and their potential applications in electrochemical energy conversion and storage, sensing, catalysis, and tissue engineering will be discussed.

Ali Mohraz received his BSc, ME, and PhD in Chemical Engineering from Azad University, The City University of New York, and The University of Michigan, respectively, and his postdoctoral training at the Frederick Seitz Materials Research Laboratory at The University of Illinois.  He is currently an Associate Professor of Chemical Engineering and Materials Science at the University of California, Irvine.  Dr. Mohraz’s primary research interests are in colloid science and complex fluids engineering, including colloidal assembly at fluid interfaces and microstructural evolution of complex fluids under transient large-strain deformations.