Research relates to current and prospective interests in design of improved materials for aerospace applications. Methodologies include electronic structure theory, chemical kinetics modeling, and molecular dynamics (including coarse-grained MD). Properties of interest include computation of transport properties (diffusion, electrochemical characteristics) and physical properties (glass transition, fragility, and density), elucidation of reaction pathways, prediction of interfacial phenomenon, and calculation of mechanical properties. More recently, emphasis has shifted to the simulation of bio-inspired materials as a function of pH, ionic strength and peptide/nucleotide sequence and structure. Projects of interest are described below:

(1) Classical and coarse-grained molecular dynamics are being conducted to simulate the assembly and function of biopolymers. Knowledge gained from these studies will be used to produce both biological and bio-inspired materials with tailored mechanical properties for a variety of Air Force applications, including structural components and templates for materials processing. For example, Nereis virens jaw protein 1 (Nvjp-1) is a protein that confers differential hardness as a function of ionic species and concentration. Hydrogels incorporating Nvjp-1 have been engineered that exhibit dramatic contraction and hardening on exposure to zinc. Our simulations aim first to predict the native structure of this highly disordered protein. Structure in hand, we seek to characterize molecular behavior, specifically the nature and location of metal-coordinated interactions and the effects of variation in pH and ionic concentrations on those interactions.

(2) Molecular dynamics simulations are being employed to evaluate the modulus, strength, and fracture toughness of polymers and composites. Automating the incorporation of quantum mechanical simulations as needed to represent bond rupture and subsequent reactions in these composites will provide an advanced framework for evaluating physical and mechanical properties in these materials at the most fundamental levels. This project is in conjunction with ongoing experimental measurements and micromechanics calculations.

(3) Atomistic simulations are being used to explore functional applications of biological macromolecules, from biosorption of valuable metals to enzymatic degradation of environmental pollutants. Subsequent analysis of properties emerging from modeling will be used to create predictive models for use in Air Force applications.

 

key words

Quantum mechanics (DFT); Classical molecular dynamics (all-atom and coarse-grained); Development of hybrid QM-MD techniques; Mechanical properties of polymer composites, assembly and structure-function relationships of bio-inspired materials; Bio-mineralization; Biopolymers; Biodegradation

Citizenship:  Open to U.S. citizens

Level:  Open to Postdoctoral and Senior applicants