The research at Diamant's group concerns the theoretical modeling of complex fluids and soft matter. Examples of relevant systems are self-assembling amphiphiles, monolayers, membranes, suspensions, liquid crystals, and polymer solutions. We have been focusing recently on the behavior of such systems out of equilibrium, their instabilities, and the resulting formation of mesoscopic non-equilibrium structures.

Examples of recent projects:

• Confined colloidal suspensions. We study the effect of confined geometry on interactions between particles in suspension. The confinement may be between two plates or in a narrow linear channel, forming a quasi-two-dimensional or quasi-one-dimensional suspension (i.e., particle motion is restricted to two dimensions or one dimension, whereas the surrounding liquid is three-dimensional). Such confinement, which is relevant to various natural scenarios and the new technology of microfluidics, qualitatively changes various interactions in the suspension, for example, the hydrodynamic coupling between particles and their dispersion (van der Waals) interactions.
   
• Topographies and instabilities in surfactant monolayers. We try to understand curious three-dimensional structrues and instabilities recently observed in surfactant monolayers at liquid interfaces, when they are subjected to lateral pressure. In particular, a newly discovered dynamic folding instability indicates the existence of stress relaxation mechanisms of surprisingly large time and length scales. These phenomena are believed to be important for the function of lungs.
   
• Non-equilibrium structures in lamellar phases. Lamellar phases are composed of amphiphilic molecules in solution, arranged in stacks of bilayer membranes. (This is not as exotic as it sounds; a lamellar phase is what cleans your hands when you wash them with soap and water.) Under stress such phases exhibit intriguing structures and dynamic transitions, for example, onion-like structures of multi-layer vesicles that form under shear, and finger-like structures (myelins) appearing under osmotic stress. We explore the mechanisms behind the formation of these non-equilibrium structures and their remarkable stability

"Increased concentration of polyvalent phospholipids in the adsorption domain of a charged protein", with E. Haleva and N. Ben-Tal, Biophys. J. 86, 2165 (2004).

"Enhanced dispersion interaction in confined geometry", with M. Marcovitch, Phys. Rev. Lett. 95, 223203 (2005).

"Surface relaxation of lyotropic lamellar phases", with H. Bary-Soroker, Europhys. Lett. 73, 871 (2006).

"Smoothening transition of a two-dimensional pressurized polymer ring", with E. Haleva, Eur. Phys. J. E 19, 461 (2006).

"Microscopic folds and macroscopic jerks in compressed lipid monolayers", with A. Gopal, V. A. Belyi, T. A. Witten, and K. Y. C. Lee, J. Phys. Chem. B 110, 10220 (2006).

To Haim Diamant's home page including a full list of publications