Ionic Liquid Structure in Thin Films

Abstract

Room Temperature Ionic liquids present an exciting opportunity to examine surface confined thin fluid films and extended interfacial systems that may prove useful for electrochemical applications. This work explores the behavior of thin (1-5000 nm) films and bulk RTIL interfaces in contact with air and silver metal surfaces. Thin films are introduced by a highly controlled dynamic wetting process. Bulk interfaces are prepared by immersing the metal electrode into an IL solution. Data from ellipsometry, vibrational spectroscopy, contact angle, and electrochemical measurements are reported for a series of Cn-3-methylimidazolium based liquids with varying length alkane tails. Results correlate chemical nature of the liquid and substrates with resulting molecular structure of the interface and behavior of the wetting film. Descriptors include chemical interactions i.e. hydrophobic forces, hydrogen bonding, van der Waals, electrostatics, etc.