Soft materials are both liquid-like and solid-like, depending on how they are examined. A familiar example is Silly Putty, which behaves like a solid on short timescales (for example, it bounces back when thrown at the wall), but like a liquid on long timescales (because it takes the shape of its container when left on the shelf for a long time).
This dual liquid/solid character, called viscoelasticity, is primarily controlled by the material’s nano- to microstructure. Colloidal gels are particulate suspensions with remarkable viscoelasticity and diverse technological applications, including the processing of catalysts, membranes, ceramics, and microfluidic device components. However, despite their technological relevance, the relationship between the microstructure and viscoelasticy of colloidal gels is still not well understood.
Chemical Engineering and Materials Science (ChEMS) Assistant Professor, Ali Mohraz, Ph.D., will use novel experimental techniques and computer simulations to better understand the viscoelasticity of colloidal gels with his proposal, “Shear-Induced Deformation and Nonlinear Rheology of Colloidal Gels,” which earned him a Faculty Early Career Development (CAREER) Award worth $400,000 from the National Science Foundation.
Mohraz and his research group will use time-resolved quantitative confocal microscopy, rheometry, and computational models of gel mechanics, to unravel the coupling between the microstructure and viscoelasticity of colloidal gels under deformation conditions that are typical during processing. Their findings will pave the way toward a better understanding of how the microstructure of soft materials control their nonlinear viscoelasticity, and will lead to improving the end-use properties of materials made from colloidal gels.
The educational component of Mohraz’s CAREER program will organize a summer outreach event called Science Week, in conjunction with fellow ChEMS Assistant Professor Young Jik-Kwon, Ph.D. The weeklong program will invite students from several local high schools to UC Irvine to conduct a series of fun and inspiring experiments, and learn more about science and engineering. Mohraz and Kwon ran a successful pilot of Science Week in 2008 with funding from a Faculty Career Development Award for Tenure-Track Faculty from UC Irvine’s Office of Academic Planning, and will expand on this foundation with an emphasis on under-represented students in the science and technology fields.
Mohraz received a bachelor’s degree in chemical engineering from Azad University in 1996, a master’s degree in chemical engineering from the City University of New York in 1999, and a Ph.D. degree in chemical engineering from the University of Michigan in 2004. His research is primarily focused on complex fluids engineering; colloid science and self-assembly of novel micro- and nano-structured materials; and composites using colloidal building blocks. Mohraz was also the recipient of the ChEMS Professor of the Year Award, presented by the Engineering Student Council in 2009, and the 2009 Fariborz Maseeh Best Faculty Teaching Award.