David M. Ronis


Department of Chemistry, McGill University
Otto Maass Chemistry Building, 801 Sherbrooke Street West
Montreal, Quebec H3A 0B8, CANADA

Tel: (514) 398-5099 Fax: (514) 398-5099 or 398-3797

Email: david.ronis@mcgill.ca

Some results of a mean-field Monte Carlo simulation
of a poly-electrolyte coated colloidal particle in dilute
and concentrated salt solutions.
(Click on the images for enlargements).

Personal Data

Ph.D. Massachusetts Institute of Technology 1978; Miller Fellow, University of California at Berkley, 1978; Camille and Henry Dreyfus Teacher-Scholar 1985; Alfred P. Sloan Research Fellow 1985; Assistant and Associate Professor, Harvard University, 1980; Professor, McGill University 1988.

Research Interests

We use the tools of statistical mechanics to solve equilibrium and non-equilibrium problems in condensed complex systems; specific examples include:

Transport in membrane and zeolite channels. In these systems, pores or channels selectively allow ions or neutral molecules to pass through the system, and play important roles in cell biology and industrial filtration processes. Our goal is to develop molecular theories of passive transport through channels in biological-membranes and zeolites that can be compared with experiment. Here are the slides of a talk I gave on this topic.

Static and dynamic properties of suspensions of highly charged colloidal particles. In many respects, dilute colloidal suspensions mimic atomic systems and can be used to study static and dynamic processes such as solidification, rheology, shear induced melting, and shear induced order or pattern formation. The Ronis group has developed several simple, but successful, theoretical models that explain many features of experiments on these systems.

Correlations and conformations in polymer-coated colloids. A key way in which colloidal suspensions are stabilized is by coating the individual colloidal particles with charged or neutral polymer chains that keep the particles from coming into contact and flocculating. Here we are developing theories to describe the coupled intra- and inter-particle interactions in systems comprised of colloidal particles coated with charged or neutral, polymeric chains, (e.g, as shown above). Our goal is to quantitatively answer the following questions: How to calculate the average distribution of neighboring colloids around any particle? What is the distribution of counter-ions in the polymer layer and in the space between the colloidal particles? What is polymer configuration and how does it change when macroscopic conditions change? What is the degree of overlap of polymer layers? Finally, what role does chemical equilibrium (e.g., that associated with weak acid/base or neutral binding equilibria) play in the conformations and correlations in these systems. Here are the slides of a talk I gave on this topic.

Surface Texturing in Polymer Extrudates. We have developed a simple theory that explains the defect texturing seen on the surfaces of extruded plastics. Our approach, while mathematically simple, brings together many ideas from works on hydrodynamics and rheology, reptation physics, the kinetics of phase transitions, and dynamical systems analysis and chaos, and describes a surprisingly rich range of phenomena including chaotic behavior ( here is an example) and pattern formation ( here is an example).

Dynamics in critical fluids far from equilibrium. We are studying turbulent fluid flow and its effects on the thermodynamics and kinetics of phase transitions in binary liquid mixtures using renormalization-group methods.

Energy-Transfer. The mechanisms of radiative energy-transfer processes in micro-particles can differ from those in the bulk, and experiments find large enhancements in the quantum yield for transfer and anomalous kinetics. We are using electrodynamic, multiple-scattering methods to explain this phenomena with applications to colloidal and cellular systems.

Representative Publications

Some Preprints and Reprints (NEW)

Here are some useful links

Links to My Past and Present Course Pages

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