Research

Fundamentals of Soft Matter

What makes soft materials unique and differentiates them from solids and liquids is their dynamic mechanical properties. These properties are intimately tied to the material’s microstructure, but the connection between the microstructure, dynamics, and bulk mechanical properties of many soft materials is not well understood. Our group investigates this fundamental problem, and how it can be exploited to engineer desired properties, in various classes of soft materials. Examples of past and current projects in this area are the microstructural origins of nonlinear rheology in colloidal gels, the physics of colloidal assembly at fluid interfaces, the mechanics of bicontinuous interfacially jammed emulsion gels (bijels), and the micro-dynamics of gelation and coarsening in attractive bimodal suspensions. A number of our research activities in this research thrust are performed at the International Space Station (ISS). Access to this microgravity environment allows us to recreate a simplified version of the problem at hand (without gravitational forces), as a first step in investigating and understanding its physics. We also collaborate with computational soft matter scientists, together aiming to develop better theoretical models to predict the behavior of soft materials. To learn more about the details of our projects, please contact Professor Mohraz.

Collaborators: Professor Safa Jamali (Northeastern University)
Selected references:
Impact of Particle Size on Droplet Coalescence in Solid-Stabilized High Internal Phase Emulsions. M. Kaganyuk and A. Mohraz, Langmuir, 35, 12807 (2019 (Featured on the Cover).
Microdynamics of dense colloidal suspensions and gels during constant-stress deformation. H.K. Chan and A. Mohraz, Journal of Rheology, 58, 1419 (2014)
Characteristics of Pickering Emulsion Gels formed by Droplet Bridging. M.N. Lee, H.K. Chan, and A. Mohraz, Langmuir, 28, 3085 (2012) (Featured on the Cover).

Engineered Biomaterials for Enhanced Tissue Response

Geometrical signals from the local 3D environment surrounding cells are known to influence their motility and function, and must be taken into account in the design of regenerative biomaterials. As an example, the topology and local curvature of porous implantable materials can strongly influence how the body responds to them, which ultimately determines the function and longevity of a number of implants and medical devices. We have a number of collaborative experimental and computational research activities that revolve around this central issue, and address it from both a fundamental and an applied perspective. We synthesize a new class of porous biocompatible and biodegradable materials with uniform negative Gaussian curvature (saddle points) along their internal surfaces and investigate how this topology influences cell-substrate interactions in the context of cell delivery, foreign body response to implants, and biofilm formation. We directly use the knowledge gained from these studies to enhance the longevity of medical devices including insulin infusion sets for the management of type 1 diabetes. Finally, we use computational modeling to gain a fundamental understanding of how local substrate surface topology impacts cell function at the single-cell level. To learn about our most recent activities in this area, please contact Professor Mohraz.

Collaborators: Professor Elliot Botvinick (UCI BME), Professor Anna Grosberg (UCI BME)
Selected references:
Microstructural characteristics of bijel-templated porous materials. K.M. McDevitt, T.J. Thorson, E.L. Botvinick, D.R. Mumm, and A. Mohraz, Materialia, 7, 100393 (2019).
Bijel-templated implantable biomaterials for enhancing tissue integration and vascularization. T.J. Thorson, R.E. Gurlin, E.L. Botvinick, and A. Mohraz, Acta Biomaterialia, 94, 173 (2019).
Composite Bijel-Templated Hydrogels for Cell Delivery. T.J. Thorson, E.L. Botvinick, A. Mohraz, ACS Biomaterials Science & Engineering, 4, 587 (2018) (Featured on the Cover).

Energy Materials Derived from Bijels

In this research endeavor we push the development of next-generation electrochemical energy storage and conversion technologies (e.g. batteries), through microstructural design. Our laboratory has pioneered a number of scalable materials processing techniques to transform a new class of soft materials, bicontinuous interfacially jammed emulsion gels (bijels), into functional electrochemically active composites with spinodal-like morphology. This unique microstructure allows us to engineer our electrodes for simultaneous delivery of large energy and power densities, bridging the world of supercapacitors with batteries. Utilizing the same microstructural design principles, we also push the performance envelope of electrolyzers and catalyst supports for more energy-efficient operation. Finally, we use computational modeling to better understand how the unique microstructure of bijel-derived materials influences the electrochemical, mechanical, and hydraulic properties of composite electrodes and porous constructs derived from them. To learn more about the details of our projects in this research thrust, please contact Professor Mohraz.

Collaborators: Professor Daniel Mumm (UCI MSE); Professor Lorenzo Valdevit (UCI MSE); Professor Regina Ragan (UCI MSE)
Selected references:
Improving Cyclability of ZnO Electrodes through Microstructural Design. K.M. McDevitt, D.R. Mumm, and A. Mohraz, ACS Applied Energy Materials, 2, 8107 (2019).
Scalable synthesis of gyroid-inspired freestanding three-dimensional graphene architectures. A.E. Garcia, C.S. Wang, R.N. Sanderson, K.M. McDevitt, Y. Zhang, L. Valdevit, D.R. Mumm, A. Mohraz, and R. Ragan, Nanoscale Advances, 1, 3870 (2019).
Microstructural tunability of bijel-derived electrodes to deliver high energy and power densities. J.A. Witt, D.R. Mumm, and A. Mohraz, Journal of Materials Chemistry A, 4, 1000 (2016).

Professor Mohraz

mohraz@uci.edu

Office

(949) 824-2028

4072 Interdisciplinary Science & Engineering Building

Laboratory

(949) 824-3246

2550 Interdisciplinary Science & Engineering Building

2550 ISEB, Bldg. #419,419 S. Circle View Dr, Irvine CA 92697