Energy dispersive X-ray reflectivity technique to study thermal properties of polymer films

Abstract

A method to study temperature dependent thickness variation of thin films has been developed based on angle and energy dispersive X-ray reflectivity (EDR) techniques. The data analysis scheme developed for this method combines both energy and angle dispersive X-ray reflectivity (ADR) profiles. The ADR technique provides the electron density profile on an absolute scale and the EDR technique facilitates rapid collection of reflectivity data as a function of temperature. We demonstrate the utility of the developed method with results of a study of thermal expansion of single and bilayer polymer films. We could detect a change of the thickness of the film in angstroms and could demonstrate interplay of negative and positive thermal expansions of dissimilar polymer layers in determining density profiles of polymer-polymer interface as a function of temperature.