Cooperative processes involve the sudden and concerted participation of a large number of basic units: amino acid residues in protein folding, proteins in fibrilization, small molecules in first-order phase transitions, complex molecules in self-assembly. The result of such concerted action is all-or-nothing observable behavior over microscopic (protein folding), mesoscopic (fibrilization), or macroscopic (phase transitions) length scales. The control of these processes by manipulation of solvent composition or thermodynamic conditions has been the unifying theme underlying our collaboration under the previous funded periods, and remains so in this accomplishment-based renewal application. Building upon our scientific achievements over the past eight years, we propose to investigate collaboratively a number of fundamental problems involving all-or-nothing behavior and its tuning: Experimental and computational studies of phase transitions in supercooled network-forming liquids of broad materials science interest; Experimental studies of the control of protein refolding by solvent tuning; Computer simulations of protein refolding rates and their control by protonation/deprotonation and solvent tuning; Computational investigation of the kinetics of water capillary evaporation in hydrophobic confinement; In each case, we seek to understand the structure, dynamics or thermodynamics of the entity undergoing a cooperative transition, and the use of solvent composition, temperature, pressure, or surface characteristics to tune the emergence of all-or-nothing behavior. Our collaboration during the past eight years has been more than the sum of its parts. The diversity of backgrounds and perspectives contributed by an experimental physical chemist (Angell), a chemical engineer (Debenedetti), and a computational physicist (Stanley) has produced findings that transcend the expertise of any one of us. Out of several examples, we highlight three: the first laboratory vitrification of a monatomic metallic liquid, made possible by theoretical and computational work on liquid-liquid and glass transitions in water-like model atomic systems; the computational discovery of protein-like cold unfolding of a hydrophobic polymer in a model solvent with two characteristic length scales, made possible by computational work on two-scalesystem thermodynamics, and theoretical work on the statistical mechanics and thermodynamics of hydrophobic hydration; the first computational calculation of the solubility of long-chain n-alkanes (up to C22) in water, and the discovery that the conformations of hydrated chains are governed to a remarkable degree by ideal gas statistics, made possible by state-of-the-art computational statistical mechanics work on polymer free energies and theoretical work on the thermodynamics of hydrophobic hydration. This accomplishment-based renewal proposal is predicated on the continuation and improvement of this collaboration.
|Effective start/end date||9/1/12 → 8/31/16|
- National Science Foundation (NSF): $390,000.00