Seeing changes in electroactive polymer films with neutron reflectivity

Taking advantage of the easy access around the D17 sample mount, together with the high flux and beam stability, an experimental configuration has been devised to simultaneously collect reflectivity and in-situ reflectance-adsorption infra-red spectra (RAIRS) of a polymer film as it undergoes a chemical reaction. The figure shows the evolution of film composition as the reaction proceeds.

By using suitable reflectance angles, changes in film structure every 200-400 s could be measured. This allows one to probe how far molecules of different sizes are able to penetrate into the bulk of the polymer film and the extent to which the hydrolysis side-reaction occurs within the film. Both of these influence attributes such as a sensor’s specificity, sensitivity and temporal response.