Neutron reflectivity determination of buried electroactive interface structure: PBT/PPy and PBT/PXV bilayers

The spatial distributions of individual polymers in multicomponent modified electrodes are determined using neutron reflectivity. A probe of the buried polymer/polymer interfaces reveals that both bilayers has electropolymerized poly(2,2'-bithiopene) as an inner, mediating layer. The outer layer is comprised of either electropolymerized polypyrrole or electroprecipitated polyxylylviologen. Neutron reflectivity data demonstrate that the very different current-potential behaviors of these devices is a consequence of the fabrication method and the consequent polymer/polymer interfacial structure. A composite structure is observed for the polybithiophene/polypyrrole film, while polybithiophene/polyxylylviologen forms a film consisting of segregated polymer layers.