The adsorption of HEC and PVA as surfactants on SrTiO3 surface: A theoretical, experimental and applied investigation

Abstract

Surfactants at solid/liquid interface could effectively improve the wettability of the liquid to the solid. Both the atomic force microscope (AFM) and theoretical calculations were applied to illustrate the mechanisms of behaviors of nonionic polymer surfactants represented by hydroxyethyl cellulose (HEC) and polyvinyl alcohol (PVA) at the solid/liquid interface of surfactant-assisted Pechini sol-gel method. The results clarified that the contact angles of surfactant-added sol reduced from64.92° ± 0.42° to 44.04° ± 0.37° and 48.53° ± 0.52° and the surfactants adsorbed on the solid in the form of disk shape, of diameter d = 500 nm and 100 nm for HEC and PVA, respectively. In addition, the adsorption energies between the oxygen atoms of the hydrophilic groups and the metal ion sites of the solid surface are -0.13 eV atom−1 for HEC and -0.04 eV atom−1 for PVA, respectively, indicating that the ion paring played a crucial role in improving the wettability of the sol to the solid. Furthermore, Bi-based superconductors with various morphologies could be prepared using surfactant-assisted Pechini sol-gel method with excellent crystallinity and transition temperatures of ∼70 K, exhibiting potential prospect in the preparation of functional oxide materials with different morphologies by wet-chemical technique.