D2O Water Interaction with Textured Carboxylic Acid-Terminated Monolayer Surfaces Characterized by Temperature-Programmed Desorption and Molecular Dynamics

Abstract

We have used a combination of temperature-programmed desorption (TPD) experiments and molecular dynamics (MD) simulations to characterize interactions between water and carboxylic acid-terminated surfaces. In the TPD experiments, D2O water interacts with alkylthiol self-assembled monolayers (SAMs) comprised of 3-mercaptopropionic acid (C3 acid), 15-mercaptopentadecaonic acid (C15 acid), 16-mercaptohexadenoic acid (C16 acid), or two-component monolayers of these constituents. Water TPD spectra exhibit broad, first-order desorption profiles with maximum desorption temperatures ranging from 168 K during desorption from the C16 acid to a maximum desorption temperature of 200 K when water desorbs from the C3 acid surface. For water desorption from the C15 acid and for the two-component surfaces, desorption traces adopt intermediate profiles between these two extremes. Desorption activation energies range from 42 and 50 kJ mol−1. In the MD studies, submonolayer concentrations of adsorbed water interact with sla...