The importance of a direct in situ evaluation of an amphiphilic diblock copolymer monolayer. The similarity and difference between its nanostructureson water and on solid substrates examined by X-ray reflectometry and atomic force microscopy

X-ray reflectometry (XR) was carried out on amphiphilic diblock copolymer p oly( a-methylstyrene)bloch-poly(decyl 4-vinylpyridine) monolayers on a wate r surface and on a glass plate. From XR data, the layer thickness and surfa ce and interface roughness were determined. For comparison, atomic force mi croscopy (AFM) was carried out on the samples deposited on solid substrates (glass and mica). From XR data, it was quantitatively clarified that the m onolayer became thicker and rougher by the deposition on solid substrates t han on the water surface. AFM revealed aggregates formed on the solid subst rates. The structural difference between the samples on a water surface and on solid substrates may be due to the preparation procedure of the sample on solid substrates. These findings indicate that the correct and precise i nformation far the structure of the monolayer on water surface can be evalu ated only by in situ experiments such as XR.