(148b) Predicting the Manufacturability of Nanoparticle Composites with Organic Coatings

The addition of metal nanoparticles in polymer matrices has been shown to drastically increase the electrical and mechanical properties of the composite material over composites produced with micron sized particles. [1] Additionally, regularly spaced and high-density nanoparticle packing can lead to better control of these properties and possibly further enhancements over randomly distributed loadings. One of the barriers to accurate control of nanoparticle distribution is a fundamental understanding of nanoparticle-nanoparticle and nanoparticle-matrix interactions.

The binding energy, density and solubility of alkanethiol ligand coated gold nanoparticles were computed with molecular dynamics simulations. Numerous parameters including surface coverage fractions, ligand-terminating groups (-CH3, -OH, -NH2), and nanoparticle orientations were considered. The analysis includes computation of minimum interparticle binding distances and energies and a check for hysteresis. We have determined a number of interesting trends and results, such as increasing binding distance with higher terminal group electro negativity and a minimum particle-particle binding energy (solubility parameter) based upon surface coverage. These results provide a fundamental understanding of ligand-coated nanoparticle interactions required for the design and production of high loading density polymer composites.

Through this effort we have been able to use molecular dynamics simulations to predict the bonding distance, cohesive energy, and solubility of alkanethiol ligand-coated gold nanoparticles. These computed results are assisting experimentalists in predicting polymer solvents that will efficiently dissolve the nanoparticles and produce well dispersed nanocomposites with high density loadings of gold nanoparticles.

References 1. Bockstaller, M. R.; Mickiewicz, R. A.; Thomas, E. L. Advanced Materials 2005, 17, (11), 1331-1349.