This award supports computational and theoretical research with a focus on developing new ways to use computer simulation to understand self-assembly of colloidal particles, objects with sizes in the range 1 to 1000 nanometers, suspended in another medium. They can be used as building blocks to create new materials that can be reconfigured and tuned by means of external electric and magnetic fields, which has become an important focal point of current materials science and engineering. Such materials find a wide range of applications, but it is poorly understood how the individual building blocks making up the material respond to fields that vary over time, such as those generated by electromagnets powered by alternating currents. The PI and his research team are developing novel computational methods that make it possible to predict and understand such properties with unprecedented accuracy, opening the way to designing responsive materials. The same algorithms also can be employed to understand and improve microfluidic devices, in which minute amounts of fluids are manipulated, for example for analytic purposes.
Computational methods developed by this project will be integrated into computer simulation packages widely used by the materials and other research communities. The PI will continue to maintain a Wiki that provides computational tools developed in his group which has become a resource to the broader computational research community.
This award supports computational and theoretical research focused on the development and application of accelerated algorithms that account for induced many-body interactions that arise from electric and magnetic polarizability. These methods will be used to explore and understand new dynamical behavior of anisotropic colloids in external fields, and to design building blocks for targeted self-assembly. The dynamics and self-assembly of colloidal particles in suspension are of widespread interest, as they allow the creation of materials with novel structures. Only recently have algorithms become available that make it possible to simulate these phenomena while taking into account fully resolved surface polarization. The PI will now exploit this approach to explore and understand the behavior of anisotropic colloids in external fields, where the electric double layer is distorted, giving rise to induced interactions or even propulsion that results in collective dynamics. Moreover, the algorithms will be extended to bulk polarizability, a phenomenon that until now has barely been explored computationally, and to a hybrid method that will accelerate the simulation of important classes of dielectric model systems by two orders of magnitude compared to what is currently possible.
Computer simulations of soft materials now routinely take into account long-range electrostatic interactions. In recent years increasing attention has been devoted to the role of dielectric mismatch ubiquitous in nature but traditionally ignored owing to its computational complexity. With prior NSF support, the PI has developed a research program that has delivered a practically usable boundary-element method capable of dealing with mobile dielectric objects. The current project applies this method to understand the propulsion mechanism in model systems of active matter and the behavior of electro-osmotic flow in microfluidic devices. Moreover, the development of an equivalent algorithm for bulk dielectrics will enable the study of materials behavior that has been virtually unexplored for want of appropriate computational techniques.
This research is timely because control over colloidal interactions is a focal point in the development of reconfigurable materials. Computational methods and resources are now able to provide direct guidance to experiments. The advances proposed here will significantly extend existing capabilities and elucidate dynamic collective phenomena as well as self-assembly driven by induced interactions.
Computational methods developed by this project will be integrated into computer simulation packages widely used by the materials and other research communities. The PI will continue to maintain a Wiki that provides computational tools developed in his group which has become a resource to the broader computational research community.
