Film formation of latex systems by scattering methods

The spatial order present in a dried latex consisting of poly(styrene) (PS) particles (diameter: 106 nm) is investigated by small-angle X-ray scatteri ng (SAXS). The process of drying is conducted below the glass transition te mperature of PS to avoid deformation of the particles when going from the c oncentrated latex to a system of close-contact particles. The assessment of spatial order rests on the analysis of the structure factor S(q) of the dr y latex. S(q) has been obtained by SAXS-measurements of the particle form f actor in the dilute latex and the scattering intensity in the dried system. Special attention is paid to the different contrast between the particles and the surrounding medium when going from the waterborne latex particles t o the dry film. It is demonstrated that the system under consideration here exhibits no true long-range order but a more liquid-like short range order . The data show furthermore that the deformation of the particles during th e process of drying must be small if not negligible.