Hierarchical Assembly of Ultranarrow Alkylamine-Coated ZnS Nanorods: A Synchrotron Surface X-Ray Diffraction Study

The packing of anisotropic ultranarrow nanoparticles (r <= 0.5 nm) in Langmuir films was investigated for two types of nanoparticles: short ZnS wires coated with tetradecylamine and ZnS rods coated with octadecylamine. In situ grazing incidence small-angle X-ray scattering (GISAXS) revealed the formation, even under zero pressure, of ordered superstructures on the water surface consisting of alternating nanoparticles. A hierarchical packing model is proposed, based on GISAXS, transmission electron microscopy, thermogravimetric analysis, and grazing incidence X-ray diffraction of pure surfactant Langmuir films.