Orientation of grafted polymer chains at the air-water interface studied by PM-IRRAS

Monolayers of polystyrene-polyethylene oxide (PS-PEO) copolymers at the air-water interface have been studied with the Modulation Polarization Infra Red Spectroscopy technique (PM-IRRAS) to measure the orientation of the PEO chains with respect to the normal to the interface. At surface densities intermediate between the dilute regime and the brush regime, the average tilt angle has been determined: it decreases continuously with the surface density in the monolayer, in good agreement with previous results (M.C. Fauréet al., Macromolecules 32, 8538 (1999)). The further stretching of the molecules in the brush regime has also been measured. No substantial volume fraction of PEO crystal domains has been detected in the very dense regime Received 16 April 1999 and Received in final form 26 August 1999