Physics of soft materials with a focus on the connection between microscopic order and macroscopic properties
Soft materials are materials whose properties are determined by internal structures with dimensions between atomic sizes and macroscopic scales. They are characterized by energies that are typically comparable to kT. As a result, they have low elastic moduli, often ~1-10 Pascals. Typical soft materials include liquid crystals, polymers, colloidal suspensions and emulsion drops. These materials, unlike conventional simple liquids, are locally heterogeneous and can have broken symmetries that affect their physical properties. Hence, although they often exhibit liquid-like behavior, soft materials also often exhibit properties of solids. Our laboratory studies the physics of soft materials with a focus on the connection between microscopic order and macroscopic properties. The underlying theme is to pursue basic understanding and address fundamental questions. However, we also address applied problems and pursue industrial collaborations since many of the materials we study can be viewed as model systems for those that are often used in applications. Current projects include (i) studying the phase and non-equilibrium behavior and properties of dense microgel suspensions, (ii) understanding the consequences of confinement and curvature over the equilibrium states of ordered materials, which in many cases require the existence of topological defects in their ground states, and (iii) electrohydrodynamics of toroidal droplets and jets.
Edited Book: Microgels Suspensions - Fundamentals and Applications, Editors: A. Fernandez-Nieves, H. M. Wyss, J. Mattsson, D. A. Weitz (Wiley-VCH Verlag & Co. KGaA, 2011).
(i) E. Pairam, J. Vallamkondu, V. Koning, B. C. van Zuiden, P. W. Ellis, M. A. Bates, V. Vitelli, A. Fernandez-Nieves, Stable nematic droplets with handles, Proceedings of the National Academy of Sciences 110, 9265 (2013).
(ii) T. Lopez-Leon, M. A. Bates, A. Fernandez-Nieves, Defect coalescence in spherical nematic shells, Physical Review E 86, 030702(R) (2012).
(iii) L. Andrew Lyon, A. Fernandez-Nieves, The Polymer/Colloid Duality of Microgel Suspensions, Annual Review of Physical Chemistry 63, 25 (2012).
(iv) J. J. Lietor-Santos, B. Sierra-Martin, A. Fernandez-Nieves, Bulk and shear moduli of compressed microgel suspensions, Physical Review E 84, 060402 (R) (2011).
(v) T. Lopez-Leon, V. Koning, S. Devaiah, V. Vitelli, A. Fernandez-Nieves, Frustrated nematic order in spherical geometries, Nature Physics 7, 391 (2011).