Dr. Blair Brettmann

Abstract

Rapid development of multifunctional, modular and easily customizable products requires an integrated approach to the product development process, both in tying molecular level behavior of the materials to macroscopic product properties and in integrating multiple scientific approaches to obtain a full picture of the fundamental material behavior. Specifically, rational prediction of functionality and stability of advanced materials requires us to understand interactions in multicomponent mixtures on the molecular scale. I will demonstrate this using a system commonly encountered in industrial formulations, the polyelectrolyte brush. These structures are often used to stabilize colloidal dispersions, but have been shown to collapse and lead to aggregation when multivalent ions are also present in the mixture. Until now, the nature of and mechanism behind this collapse was not understood, leading to difficulties in predicting the behavior of these systems. Through a combination of theory, simulations and experiments, my collaborators and I have demonstrated that the brush collapses into nanoscale “pinned micelles” due to a combination of solvophobic and electrostatic bridging effects. This fundamental understanding leads to better prediction of collapse transitions in these colloidal dispersions and capabilities for rational design of new, stimuli-responsive materials.