Charge-transfer reactions between metals and polyimides

In order to investigate the dependence of reactions of electropositive metals with electroactive polymers on their respective electrochemical redox potentials, the authors report herein the results of studies on the evolution of the Cr/PI and Ce/PI interfaces, the effect of Cs dosing of PI, and electrochemically reduced PI films and monomeric diimides. The results described here, in conjunction with the work of others, support a mechanism involving electron transfer from metals to polyimides, the degree of which depends on the relative matching of their redox potentials. For electropositive metals, electron transfer paves the way for subsequent polymer activation and eventually strong interface adhesion. For metals whose redox potentials lie far positive of polyimides, self reactions such as clustering, agglomeration and diffusion are the most accessible pathways available upon deposition. This mechanism, when extended to other systems may offer a means for predicting the interaction of metals with electroactive polymers. The authors are currently testing the applicability of such a model for polymer-on-metal systems.