Abstract
This work is focused on the enhancement of the monolayer stability by studying the pH-dependent adsorption of metal ions of varying valence to a stearic acid monolayer. The stability of the monolayer was detected by measuring the time-dependent change in the mean molecular area at a constant surface pressure. A rather narrow ion-specific pH range of maximum stability was found. Within this pH range, the monolayer acted almost as an ideal film and the molecular area at a predetermined surface pressure remained constant for several hours. The stability was correlated with the degree of dissociation of the monolayers which was determined by X-ray photoelectron spectroscopy. The observed p K a values were 4.3 for Tb stearate, 5.6 for Cd stearate and 6.2 for Mn stearate. The deposited multilayer structures were analyzed by atomic force microscopy. The films deposited at a pH of poor stability clearly contained more defects than the films fabricated at a pH of maximum stability. The resolution of the images was sufficient for a detailed crystallographic analysis of the molecular packing.
Published Version
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call