Characterizing the phases of Langmuir monolayers of cylindrical brushes with x-ray reflectivity and diffraction

Langmuir monolayers of polymacromonomers (cylindrical brushes) with poly(vinyl)pyridine side chains of different length, polyPV P20.8 and polyPV P46.7, are studied at the air?water interface by means of x-ray diffraction and reflectivity. The advantages of measurements on an aqueous subphase, which contains NaI, are demonstrated. This subphase does not affect the structure of an uncharged monolayer, although NaI is incorporated into the side chains, it provides an enhanced contrast for the x-ray investigations. A structural transition from aligned single molecules to a homogeneous monolayer is found, which is attributed to intra-?and intermolecular interactions.