The self-assembly of nanoparticles at liquid-liquid and liquid-air interfaces has becoming an efficient way to create two-dimensional arrays with tunable electrical, optical, magnetic, and mechanical properties. In these arrays, inorganic nanoparticles are coated with a shell of ligand molecules that interlock as spacers and provide tensile strength.  We have  discovered recently that the heterogeneous environment, such as an air-water interface, strongly influences the membrane properties.  Highly quantitative surface X-ray scattering shows a difference of ~6Å in average ligand shell thickness between the  two sides of the membrane, corresponding to ~30% of the extended ligand length.  Experiments and molecular dynamics simulations further elucidate the role and interplay of ligand coverage and mobility in producing and maintaining this asymmetry, even after the water is removed and the membranes become free-standing.  Thermomechanical response of membrane shows hysteretic behavior, which is attributed to reorganization of ligand at high temperature by comparing experimental data with molecular dynamic simulation.  Understanding this ligand distribution asymmetry opens up new avenues for designing nanoparticle superstructures.<br/>

Effect of ligand asymmetry in the properties of nanoparticle membrane

253rd National Meeting (2017)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.