Using Dispersions of Soft and Rigid Vesicles to Stabilize Suspensions Against Sedimentation

Purdue University, West Lafayette IN

Investigators

Abstract

Many paint, ink, and pharmaceutical products are suspensions of microscopic particles in a water-based liquid. The performance of these and similar products can be compromised if the particles agglomerate or stick together or if they sediment over long periods of time. Usually, a chemical is added to the mixture to act as a “dispersant,” which prevents or slows down agglomeration and settling of the particles. This project focuses on certain dispersants that form “vesicles,” which are balloon-like flexible spherical containers in which a microscopic membrane completely encloses a water-like region. Dispersants that form vesicles can efficiently prevent particle agglomeration and sedimentation for a wide variety of particle types and sizes. For example, dispersants that form vesicles in various inks has been shown to improve their performance and reduce production costs. The project will use experimental, theoretical, and computational methods to better understand how the formation of vesicles stabilizes suspensions. The project will also evaluate several other dispersants to tailor their effectiveness to specific particle types. Finally, the project will allow undergraduate students to participate in a unique summer research program and will provide interesting and practical examples that can be easily introduced into various engineering courses. This project focuses on the physicochemical mechanisms underlying the use of vesicles and liposomes to control the stability of various suspensions. A combination of experimental, theoretical and computational methods will be used to generate insights into vesicle and liposome dispersion behavior and improve the understanding of these types of complex fluids. The project will screen, evaluate, and select those surfactants which form liposomes and vesicles and establish rigorous property-stabilization relationships. Innovative methods, such as static light scattering and small-angle x-Ray scattering (SAXS), will be employed to determine the intra-vesicle and inter-vesicle microstructures that form and how they prevent particles from settling. This project will also yield a robust and well-tested set of tools for future studies of technologically relevant colloidal suspensions and dispersions. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.