(Invited) Mechano-Chemical Coupling at Interfaces in Novel Hybrid Materials

Abstract

The strong coupling between chemistry or electrochemistry and mechanics at interfaces may be exploited for designing materials with unexpected functional behavior. One example is provided by nanoporous-metal based hybrid materials that behave similar to piezoelectric ceramics: Bodies of nanoporous gold impregnated with electrolyte emit exceptionally robust electric signals when subjected to external load. The metal-based material may thus be considered as piezoelectric, in a literal interpretation of the term. Another example is a class of novel phenomena in which the mechanical response to load – which may be elastic or plastic – can be tuned by an electric potential. The relevant capillary parameters can be either, surface stress or surface tension. In each case, a coupling between the capillarity and electricity is crucial, and the coupling strengths can be quite different. While the energy-charge coupling at a surface is described by the Lippmann equation, a predictive understanding of the interfacial stress-charge coupling, which governs the apparent piezoelectricity, remains elusive. The talk will discuss relevant issues from the perspectives of experiment, phenomenological thermodynamics, and atomistics.