Invited Paper SS-ThM10
Structural Transitions of Ionic Liquids at Nanoconfined Interfaces
Thursday, November 10, 2016, 11:00 am, Room 104D
Ionic liquids (ILs) have remarkable properties including vanishingly low vapor-pressures, are non-flammable, and have wide thermal and electrochemical stability windows that make them ideal for several applications, including electrolytes in supercapacitors and lubricants. Our interest is to understand the interfacial behavior of ILs under nanoconfinement. Several studies have demonstrated the layered structure of ILs in nanoconfinement. The confined ions resist being “ squeezed out” when surfaces are compressed, with the result that an IL film remains between the surfaces up to high pressures, thus preventing direct contact between the surfaces, also under shear, which can aid in reducing friction.Laboratory studies have mainly focused on atomically flat and chemically homogeneous substrates, i.e. on ideal surfaces, to understand fundamental mechanisms. In our current work we are exploring the influence of nanoscale heterogeneities on ionic-liquid interfacial properties. Such heterogeneities can be composed of contamination, roughness or chemical surface groups. The strong molecular interactions still facilitate self-assembly of ILs on the surfaces, but they reveal new aspects of the IL behavior. We address diverse fundamental questions about the interfacial IL structure and the response to shear in the presence of heterogeneities. Further, these studies are of relevance to extend studies performed on ideal systems to real applications.