RUI: Chain Conformation and Collapse in Polymer Systems: Mapping a Many-Body onto a Few-Body Problem

点击翻译按钮获取中文摘要

TECHNICAL SUMMARY:This award supports research and education in theoretical polymer physics. The research focus addresses the problem of explicit solvent effects on polymer chain conformation. Because the complex structure of a polymer, whether synthetic or biological, depends on the fluid in which it exists, it is necessary to either include the details (e.g atoms in a host liquid) or employ an effective medium approximation adequate to predict polymer chain conformation. The research carried out in this effort replaces the complex environment by suitably accurate (and more complicated) effective interaction. The approach feeds into the general field of multiscale modeling, especially in polymeric systems. The domain of validity of the approach and the accuracy of its extensions are primary interests of the research.The center piece research effort develops a detailed theoretical understanding of the coupling between polymer conformation and solvent properties. A simple, yet realistic continuum based interaction-site model is used in which both polymer and solvent are built from "simple-liquid" monomers. The approach maps the many-body chain-in-solvent problem onto a few-body single-chain problem via the introduction of a set of site-site solvation potentials. This approach fully incorporates the local solvent structure into the solvation potentials.The research evolves from recent work by the PI that (i) establishes the validity of a pair-wise decomposition of the exact many-body solvation potential for a short chain in a simple-liquid solvent and (ii) successfully applies short chain solvation potential results to long-chain systems. These initial results indicated the potential application to a broad range of systems. The research of this award focuses on the extends the approach to a larger class of interaction potentials and thus more realistic systems, including asymmetric systems in which the polymer and solvent are built from different interaction sites and to systems with molecular (and polymeric) solvents. The effects of solvent on chain conformation and collapse, as well as multi-body correlations, are studied in each of these systems.The activities undertaken have broad impact beyond the specific research problems. This research represents an important step towards the goal of developing a complete theory of polymeric liquids based on the rigorous techniques of liquid state physics. The approach provides a straightforward way to account for solvent effects in polymer systems without having to perform computationally expensive full-solvent simulations. The results of this research are disseminated both through publication in scientific journals and through presentation at local, regional, and national meetings. The research program has been designed to allow for maximum student participation by dovetailing into the physics curriculum at the PI's college. Computation and simulation methods taught in the core physics courses establish a direct link between classroom learning and this research program and provide students with the tools needed to make meaningful contributions to this work. The undergraduate students who participate in this research benefit by learning state of the art computer simulation techniques and have opportunities to present at scientific meetings. This research continues a track record of mentoring undergraduates as researchers and successfully fostering their advancement to graduate study in science and engineering. NONTECHNICAL SUMMARY:This award supports research and education in theoretical polymer physics. The research focus addresses the problem of predicting the shape of long polymers when dissolved in different solvents. Because the complex structure of a polymer, whether synthetic or biological, depends on the fluid in which it exists, it is necessary to either include the details (e.g thousands of atoms in a host liquid) or employ an approximation to accurately predict polymer chain conformation. The research carried out in this effort replaces the complex environment of the host liquid by suitably accurate (and more complicated) set of rules for how the atoms of polymer interact with each other. The domain of validity of the approach and the accuracy of its extensions are primary interests of the research.The center piece research effort develops a detailed theoretical understanding of the coupling between polymer shape and solvent properties. A simple, yet realistic model is used in which both polymer and solvent are built from "simple-liquid" pseudo-atoms. The approach maps the complex polymer-in-solvent problem onto a simpler polymer-only problem.The activities undertaken have broad impact beyond the specific research problems. This topic is of broad importance since the overall properties of dissolved polymers, including polymer solubility, solution viscosity, and functionality, are intimately linked to the underlying microscopic configuration of the individual polymer molecules. The results of this research are disseminated both through publication in scientific journals and through presentation at local, regional, and national meetings. The research program has been designed to allow for maximum student participation by dovetailing into the physics curriculum at the PI's college. Computation and simulation methods taught in the core physics courses establish a direct link between classroom learning and this research program and provide students with the tools needed to make meaningful contributions to this work. The undergraduate students who participate in this research benefit by learning state-of-the-art computer simulation techniques and have opportunities to present papers at scientific meetings. This research continues a track record of mentoring undergraduates as researchers and successfully fostering their advancement to graduate study in science and engineering.