MECHANISM OF SOLID LIQUID INTERFACIAL REACTIONS - ATOMIC-FORCE MICROSCOPY STUDIES OF THE SELF-PASSIVATING REACTION BETWEEN SOLID P-CHLORANIL AND AQUEOUS-PHASE N,N-DIMETHYLPHENYLENEDIAMINE/

The reaction between solid p-chloranil and alkaline aqueous solutions of dimethylphenylenediamine is shown to be self-passivating owing to t he formation of insoluble product at the reacting interface. In situ a tomic force microscopy imaging of the reaction occurring at (010) surf aces of single crystals of p-chloranil show that the nucleation of the overgrowth is progressive and that its coverage, S, follows the time (t) dependence S(t) = 1 - exp(-k(3)t(3)), where k(3) is a rate constan t. Measurement of the z piezo voltage throughout the reaction to give an absolute measure of the surface height shows that appreciable (hydr oxide driven) dissolution occurs prior to the formation of the overgro wth and the surface becoming fully passivated.