AVS 65th International Symposium & Exhibition | |
Biomaterial Interfaces Division | Thursday Sessions |
Session BI-ThA |
Session: | Biolubrication and Wear / Women in Bio-surface Science |
Presenter: | Markus Valtiner, Vienna University of Technology, Austria |
Authors: | H.-W. Cheng, TU Wien, Germany H. Weiss, Max Planck Institute for Polymer Research, Germany M. Mezger, Max Planck Institute for Polymer Research, Germany M. Valtiner, Vienna University of Technology, Austria |
Correspondent: | Click to Email |
Bio and aqueous applications of ionic liquids (IL) such as catalysis in micelles formed in aqueous IL solutions, lubrication or extraction of chemicals from biologic materials rely on surface-active and self-assembly properties of ILs. Here, we discuss qualitative relations of the interfacial and bulk structuring of water-soluble and highly surface-active ILs on chemically controlled surfaces over a wide range of water concentrations using both force probe and X-ray scattering experiments. Our data indicate that IL structuring evolves from surfactant-like surface adsorption at low IL concentrations, to micellar bulk structure adsorption above the critical micelle concentration, to planar bilayer formation in ILs with <1 wt % of water and at high charging of the surface. Interfacial structuring is controlled by mesoscopic bulk structuring at high water concentrations. Surface chemistry and surface charges decisively steer interfacial ordering of ions if the water concentration is low and/or the surface charge is high. We also demonstrate that controlling the interfacial forces by using self-assembled monolayer chemistry allows tuning of interfacial structures. Both the ratio of the head group size to the hydrophobic tail volume as well as the surface charging trigger the bulk structure and offer a tool for predicting interfacial structures. Based on the applied techniques and analyses, a qualitative prediction of molecular layering of ILs in aqueous systems is possible. Potential applications in biomedical applications will be discussed.