CAREER: Multi-Scale Modeling of Self-Assembly and Structural Transitions in Amphiphilic Systems

University Of Florida, Gainesville FL

Investigators

Abstract

PROPOSAL NO.: 0644089 PRINCIPAL INVESTIGATOR: Kopelevich, Dmitry INSTITUTION NAME: University of Florida TITLE: CAREER: Multi-Scale Modeling of Self-Assembly and Structural Transitions in Amphiphilic Systems Multi-Scale Modeling of Self-Assembly and Structural Transitions in Amphiphilic Systems Intellectual Merit. Dynamics of self-assembly and structural transitions in amphiphilic (micro & nano-enclosed shaped) systems play an important role in numerous industrial processes, ranging from rheology of complex polymer fluids to transport in biological cells. Theoretical and computational modeling of these processes is extremely challenging due to the large span of length- and time-scales involved. The goal of this research project is to develop a multi-scale approach to investigation of dynamics of self-assembled structures. This goal will be accomplished through reduction of molecular-level models to stochastic models for dynamics of few relevant degrees of freedom (reaction coordinates). The developed stochastic description will permit investigation of complex amphiphilic systems over length- and time-scales that are not achievable by molecular dynamics simulations and yet maintain all the information pertinent to a specific process. The parameters for the stochastic models will be obtained from a series of constrained and unconstrained molecular dynamics simulations. Identification of appropriate reaction coordinates will be an important component of the proposed model development. It is anticipated that some of the reaction coordinates (such as a collective mode representing internal micellar microstructure) will play a significant dynamic role in some processes (such as addition of a surfactant to a micelle) while will be negligible and can be approximated by thermal noise in other processes (such as removal of a surfactant from a micelle). The elucidation of relevant reaction coordinates and possible cooperative effects between them will be achieved by examination of time-scales of different modes. The developed stochastic model will be applied to dynamic processes in several amphiphilic systems of technological and fundamental importance, namely micellar formation and disintegration, coalescence of reverse micelles, formation of dynamic cross-links in solutions of worm-like micelles, and fusion of lipid bilayers. Therefore, the systems to be considered provide examples of both micellar solutions and continuous phases. Broader Impacts. The fundamental understanding of the structural transitions in self-assembled systems, gained in the course of the project, will have a significant impact on nano-technological applications. For instance, design of efficient processing routes toward nano-structured materials templated by surfactant molecules and development of nano-reactors will be greatly facilitated. In addition, one of the structural transitions studied in this work, fusion of lipid membranes, plays a crucial role in multiple transport processes within biological cells (related to bio-technology applications). An understanding of these processes will have an impact on development of new medical technologies. It is also expected that the stochastic modeling framework developed in this research will find applications in multi-scale modeling of a broad range of complex systems. Introducing undergraduate and high-school students to research stimulates their interest in pursuing science or engineering career by challenging them at early stages of their educational experience. In addition, introducing the contemporary issues into the undergraduate curriculum will prepare the students for the changing landscape of the chemical engineering profession, including emerging nano- and biotechnologies. The PT plans to engage in several K-12 outreach activities, namely hosting high-school students in his lab and developing molecular dynamics demonstration materials for the Engineering Fair at the University of Florida. An integrated educational component will be developed that is aimed at teaching principles of molecular dynamics and nanotechnology within the chemical engineering curriculum. The P1 is participating in the development of a course sequence on nanotechnology and its environmental and health impacts. The P1 also plans to maintain strong undergraduate participation in his research program and to actively encourage students from underrepresented minority groups to participate in his research.