Ultra-small-angle X-ray scattering study of the structure of colloidal and polymeric systems

We have constructed the Bonse-Hart type Ultra-small-angle X-ray Scattering (USAXS) instrument to study large-scale density fluctuations in colloidal and polymer systems. Our USAXS instrument has very high small-angle resolution up to 8 micrometers. The USAXS curves from polymer latex dispersions at very low ionic strength showed clear Bragg peaks, indicating that the ordered structure of latex particles was formed even inside dispersions by the electrostatic interactions between the particles. The lattice system and lattice constant could be precisely estimated. The time evolution of the USAXS curve reflecting the ordered structure formation was also examined. The microdomain structure of polymer alloy systems and microcrystalline structure of polypropylene film were also investigated. The USAXS technique enables us to investigate submicron structures in various systems which could not be studied by other technique