This award supports computer modeling, theoretical research and education to apply the principles of statistical physics to gain insights on competitive polymer hydration in nanomaterials. Polymers are long chain-like molecules, some of which can form weak electrostatic bonds, known as hydrogen bonds, with water or other solvents. Many nanotechnological applications such as nanomedicine, purification, and sensing employ biocompatible water-soluble polymers that may be grafted to surfaces or part of a larger self-assembled supramolecular structure. To a large extent the properties of these nanomaterials depend on polymer hydration, that is, the interactions between the polymers and the surrounding water molecules. Competitive polymer hydration reflects the fact that there is a competition for the formation of polymer-water hydrogen bonds with other chemical components of the system. This competition can lead to changes in polymer size and shape, which may affect the properties of the nanomaterial. The PI aims to use computer simulation to investigate the factors affecting polymer hydration and the organization of the surrounding water in polymers grafted to surfaces or forming larger self-assembled structures. The PI will study competitive hydration involving the presence of additional solvents, such as alcohols, and the presence of biologically relevant simple sugars, such as fructose and glucose, which are typically encountered in many nanomaterial applications. Fundamental understanding of polymer hydration is essential for proper functioning of nanomaterials, designing new responsive materials, and optimizing their performance. This research will contribute to theoretical understanding of the properties of polymer-grafted nanostructures and create a basis for comparison of competitive hydration in nanostructures of different geometries, for example planar vs. curved surfaces, exposed to multicomponent solutions. This project will also provide insights into molecular transport through nanopores thereby bridging polymer science and biophysics. Graduate and undergraduate students will be trained in modern simulation methods and data analysis. The results of this research will enhance graduate courses on polymer and soft matter physics as well as stimulate interest in STEM graduate and undergraduate research and education.
This award supports computer simulation and theoretical research, and education to understand the effects of competitive solvation and nanoconfinement of water-soluble polymers grafted to surfaces of different curvature. Solubility of many macromolecules depend on hydrogen bonding with water. Hydrogen bonding is a highly competitive interaction and susceptible to external conditions, which may alter the balance between acceptors competing for donors or vice versa. The outcomes of such an intricate balance are often hard to anticipate and hydration is rather difficult to measure experimentally. Computer simulations are a good tool for studying hydration and hydrogen bonding. Using largescale atomistic molecular dynamics simulations, the PI will investigate water structuring and hydration of polyethylene oxide grafted to solid nanopores, the effect of synthetic and carbohydrate co-solvents on polymer conformation, and the properties of polymer brushes grafted to convex, planar and concave gold surfaces or as part of a self-assembled micelle structure. The research group will investigate proton donating and proton accepting co-solvents and analyze hydration dynamics and competition for hydrogen bonding between inter- and intramolecular hydrogen bonding with polymer brushes leading to conformational changes and to triggering pore opening/closing in a solvent or temperature-dependent manner. The influence of polymer length, grafting density, size, surface curvature, co-solvent concentration, shape, hydrophobicity and chemical origin, whether synthetic or biological, on competitive hydration will be systematically studied. Based on simulation data analysis, experimentally testable predictions will be made regarding co-solvent-triggered changes in the polymer brush properties including control over the polymer-grafted nanopore transport or surface interaction of polymer-grafted nanoparticles and micelles, as used in biomedical applications. This project will provide ample opportunity for graduate and undergraduate student training in modern computational skills which can be applied in different scientific and nanotechnological areas.
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.
