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Research Abstracts Online
January 2008 - March 2009

University of Minnesota Twin Cities
Institute of Technology
Department of Chemical Engineering and Materials Science

PI: H. Ted Davis, Fellow

Modeling of Soft Materials and Complex Fluids

The addition of a few percent of diblock copolymers to epoxy leads to a huge increase (some factor of 50) in the toughness of the cured epoxy. It is known, from transmission electron microscopy, that the diblock copolymers form spherical and cylindrical micelles with a radius of ~100 nanometers. It is surprising that these soft inclusions can increase the toughness of cross-linked epoxy so dramatically. There is currently no theoretical understanding of this behavior. In order to determine the origin of this effect, these researchers are simulating the toughness of simple elastic crosslinked networks with soft inclusions. In particular, they are modeling epoxy using large random elastic networks of stiff springs with soft inclusions modeled as domains of springs with reduced spring constants. This project involves the use of molecular dynamics and/or Monte Carlo simulation techniques to determine the toughness of these networks, and the effect of the shape and size of soft inclusions.

Another project involves the use of particle-based simulation techniques to study the dynamics and rheology of complex fluids such as polymer solutions and melts, biological macromolecules, colloids, and amphiphilic mixtures and membranes. Complex fluids present a challenge for conventional simulation techniques due to the importance of thermal fluctuations and the presence of disparate time scales. The unique problems associated with the modeling and analysis of these systems has led to the development of new coarse-grained simulation techniques that mimic the behavior of atomistic systems on the length scales of interest. This project involves the development and implementation of advanced simulation techniques for studying this class of problems. The supercomputers are used to support the development and application of a new particle-based simulation technique to binary and ternary mixtures, and polymer solutions.

Group Members

William R. Casper, Supercomputing Institute Undergraduate Intern
Erkan Tüzel, Research Associate