Title: Applications of mesoscale modeling – towards computer simulation of cleaning.

Fiona Case
Case Scientific, 125 Main Street, Essex Junction, VT 05453


Liquids that contain mesoscale structures between nanometers (10-9m) and microns (10-6m) in size are challenging to study, and yet phenomena that occur at this scale determine the properties of  many scientifically and commercially important materials. These include personal care products such as liquid hand soap or shampoo, cosmetics, foods, paints, detergents, the microencapsulation or delivery systems for drugs, and emulsion polymerization. Mesoscale behavior is prohibitively expensive to model using atomistic based simulation techniques (such as molecular mechanics). Yet because of their sub-micron structure these materials cannot be fully characterized by their bulk behavior, or modeled using continuum models. Mesoscale modeling techniques have been developed to study these types of materials. The most successful is Dissipative Particle Dynamics (DPD). Starting from a random distribution of model surfactants, oil and water DPD can predict the formation emulsion structures as a function of surfactant head and tail size ratio (1). New work shows that DPD can also predict the formation of oil-in-water emulsions as surfactants solutions remove oil from a surface. This suggests that the technique may be able to model key processes in cleaning.

1) G. Broze, G. and F. H. Case,  “Impact of Mesoscale Structure and Phase Behavior on Rheology and Performance in Superwetting Cleaners”, Chapter 24 in “Mesoscale Phenomena in Fluid Systems” ACS Symposium Series #861, edited by F. H. Case, P. and Alexandridis, ACS Press, 2003.

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