Diamond colloidal crystal in a cholesteric liquid crystal

collidal diamond-lattice with defect linesSpherically symmetric colloidal particles and suspensions have been extensively studied, both theoretically and experimentally.  While spherical colloids in isotropic fluids have many potential uses, particles with anisotropic interactions have a much higher potential as the synthetic building blocks for self-assembled materials with desirable properties, such as a photonic band-gap, at the nano- or micro-scale.  The anisotropic nature of liquid crystals (LCs) makes them an ideal candidate to generate non-spherically symmetric interactions between colloidal particles. In a recent article, we adjust the pitch in a cholesteric liquid crystal in order to give rise to the most energetically favourable colloid-defect structure, commensurate with the diamond lattice. This structure corresponds to defect lines travelling along symmetry axes in the diamond crystal. Once formed our diamond lattice should be stable against thermal fluctuations.

Biopolymer filltration in corrugated nanochannels

Polymer in troughRecent developments in promising micro and nanofluidic technologies have sparked a renewed interest in the statics and dynamics of confined polymers. In a recent letter, we examine pressure-driven nonequilibrium transport of linear, circular, and star polymers through a nanochannel containing a rectangular pit with full hydrodynamic interactions and thermal fluctuations. We demonstrate that with sufficiently small pressure differences, there is contour length-dependent entropic trapping of the polymer in the pit when the pit and the polymer sizes are compatible. This is due to competition between flow and chain relaxation in the pit, which leads to a nonmonotonic dependence of the polymer mobility on its size and should aid in the design of nanofiltration devices based on the polymer size and shape.

Welcome!

Our research focuses on modelling particles and dynamic processes in complex fluids.  We study systems involving micro- and nano-scale objects, soft colloids or polymers for instance, in a complex fluid such as a liquid crystal.  An important aspect of our work is the development of models and multi-scale computer simulation techniques to investigate these systems.

If you are interested in joining our group, please send me an email. We accept applications any time of the year. For more information about applying to the graduate program in Applied Math at Western, see our web page.