ANOMALOUS ETCHING KINETICS OF SELF-ASSEMBLED MONOLAYERS ON SILICA-WATER INTERFACES - EXPERIMENT AND MODELING

We have studied the etching of siloxane/silica self-assembled monolaye rs in basic alcohol solutions using second harmonic generation, The ki netics of the etching process takes an unusual algebraic power law tim e dependence, with an exponent of 0.5, On the basis of the chemical na ture of our system, we propose a surface cleavage mechanism and a surf ace diffusion based reaction model. We also perform Monte Carlo simula tions on the system, When the solvent shell effect is considered as a geometric constraint for surface adsorption, we reproduce the anomalou s power law.