X-ray reflectometry confirms polymer-grafted silica particle monolayer formation at the air-water interface

We examined the air-water interface of the poly(methyl methacrylate)-grafted silica particle monolayer by X-ray reflectometry to obtain in situ information on the particle monolayer structure suggested by pi-A isotherm measurement and SEM observation. We confirmed the monolayer formation of polymethylmethacrylate-grafted silica particle at the air-water interface by interesting XR profile. We obtained XR profile with many tooth-shaped fringes for one of the PMMA-grafted silica particle monolayer. By the model fitting of this profile, we confirmed monolayer formation at the air-water interface. Furthermore, we found that the interface roughness became large at the plateau region in the pi-A isotherm, which provides insight into the origin of the plateau region. We confirmed the reproducibility of XR profiles at same surface pressure after surface compression. This indicates the structually-reversible nature of the particle monolayer, which is the unique nature of the polymer-grafted particle monolayer.