COMP 94 |
| We performed all-atom molecular dynamics simulations to study the friction between two surfaces coated with zwitterionic materials immersed in water with two regions of bulk water placed on both sides of the surfaces. We have shown recently that zwitterionic materials, including phosphobetaine, sulfobetaine, and carboxybetaine, are superlow biofouling due to their strong hydration layers at the interfaces. Superlow biofouling materials with low friction are desirable for applications in BioMEMS/NEMS. In this work, ab initio quantum chemical calculations were first performed to characterize these zwitterionic groups and accurate force fields were developed. Then, molecular mechanics was applied to select optimized packing patterns and structures. Sodium and potassium ions were employed as model ions to study their effects on friction coefficients. The effect of their concentrations was also investigated. Results show that (a) higher concentrations of sodium ions result in larger friction coefficients due to the weakening of surface hydration shells and (b) the systems with sodium ion solutions possess larger friction coefficients than those with potassium ion solutions due to the stronger solvation ability of sodium ions. Results from this work are compared with those of poly(ethylene glycol). The relationship among friction, nonfouling, and ion solvation will be discussed. |
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Bold Predictions in Theoretical Chemistry: A Poster Session in Honor of One of the Boldest, Bill Goddard, on the Occasion of his 70th Birthday
7:30 PM-9:30 PM, Sunday, August 19, 2007 BCEC -- Exhibit Hall - B2, Poster
Division of Computers in Chemistry |