AVS 50th International Symposium
    Thin Films Wednesday Sessions
       Session TF+MM-WeA

Paper TF+MM-WeA3
Behavior of Thin Ionic Liquid Films Studied with Atomic Force Microscopy

Wednesday, November 5, 2003, 2:40 pm, Room 326

Session: Sensors, Smart Films and Functional Materials
Presenter: J.J. Nainaparampil, AFRL/MLBT
Authors: J.J. Nainaparampil, AFRL/MLBT
B.S. Phillips, AFRL/MLBT
K.C. Eapen, University of Dayton Research Institute
J.S. Zabinski, AFRL/MLBT
Correspondent: Click to Email
Ionic liquids (IL's) represent a new class of solvents having the character of molten salts. They have no detectable vapor pressure, are moisture, air and temperature stable and therefore are excellent solvents. Most of these IL's consists of cations such as different alkyl imidazolium or alkyl pyridinium ions and anions such as BF@sub 4@, PF@sub 6@, N (CF@sub 3@SO@sub 2@)@sub 2@, CF@sub 3@SO@sub 3@. In this work, crystals of alkyl imidazolium+ PF@sub 6@ are dissolved in water or acetonitrile to form 0.2% to 0.5% solutions and deposited on Si surface to form thin films. Atomic force microscope working in non-contact mode capable of providing biased tip lithography is used to characterize these films. It is observed that scanned films give rise to certain geometrical structures that are repeated in recrystallized surfaces. A biased AFM tip is used to mobilize these structures to form other complex structures. It is noted that the same solution, when used as a lubricant in sliding contacts gives rise to drastic friction reduction compared to other lubricants. These IL’s were used to lubricate a micro electro mechanical system (MEMS) electro static output motor. Results from MEMS endurance tests and an interface model that is based on the AFM study will be presented. Electro-migration of crystallites and adhesion of transfer films affect the friction and durability significantly.