Adsorption of sorbitan ester surfactant on copper and Cuprous oxide surfaces: A density functional theory study

Abstract

This work reports a detailed density functional theory study of the adsorption of sorbitan monoacetate (SMA) molecules -as a model of the head group of sorbitan-derived surfactants- on Cu (111) and Cu2O (111) surfaces. Our study includes the most stable adsorption configurations, considering the electron-withdrawing nature of the molecule functional groups and the electron-donating sites on the surface. When SMA adsorbs on Cu (111), van der Waals interactions emerge as the most stabilizing components. In contrast, for Cu2O (111), SMA binds through coordination bonds hydrogen bonds. Charge transfer analysis in the formed Cu-O bonds showed that molecule's oxygen atoms behave as electron withdrawers whereas Cu atoms as electron-donating entities. The non-covalent index analysis revealed that van der Waals interactions in both systems present an attractive component.The results presented help explain how span surfactants head group interacts with Copper and Cuprous oxide (111) surfaces, what type of bonds and interactions are present in the adsorption process, and how strong they are to assess its applicability in area selective deposition techniques as an easily removable Copper passivating agent. Also, the clarified interactions appearing in this metal–organic system may be of great interest for the design of sensing nanodevices.