AVS 56th International Symposium & Exhibition
    Biomaterial Interfaces Friday Sessions
       Session BI+AS+NS-FrM

Paper BI+AS+NS-FrM6
Spatially Selective Deposition of a Zwitterion with Alkyl Pendant Groups on Periodically Poled Lithium Niobate

Friday, November 13, 2009, 10:00 am, Room K

Session: Micro and Nanoengineering of Biointerfaces II
Presenter: Z.Z. Zhang, University of Nebraska-Lincoln
Authors: Z.Z. Zhang, University of Nebraska-Lincoln
J. Xiao, University of Nebraska-Lincoln
D. Wu, North Carolina State University
A. Gruverman, University of Nebraska-Lincoln
L. Routaboul, Université Louis Pasteur Strasbourg, France
P. Braunstein, Université Louis Pasteur Strasbourg, France
B. Doudin, Université Louis Pasteur Strasbourg, France
O. Kizilkaya, Louisiana State University
C. Borca, Paul Scherrer Institute, Switzerland
P.A. Dowben, University of Nebraska-Lincoln
Correspondent: Click to Email
We have spatially selectively deposited a zwitterion compound from the class of N-alkyldiaminoresorcinones (or 4,6-bis-dialkylaminobenzene-1,3-diones, C6H2(NHR)2(O)2), compounds, where R =C5H11. These molecules have very strong local dipoles as the delocalized benzene π molecule of the zwitterion “core” loses aromatic character due to the large charge separation. This charge separation provides this type of zwitterion molecule with a large electric dipole moment across the “benzene” like plane. Unlike the ferroelectric materials, the electric dipole of this class of zwitterions when adsorbed on metal surface (and most substrates) is not switchable, which makes these zwitterion compounds more like an electret. We have been able to demonstrate that at least one of this class of zwitterion compound will selective adsorb from solution on periodically poled lithium niobate substrates using infra-red spectra-microscopy. The spatial localization zwitterion on lithium niobate suggests that the ferroelectric poling of lithium niobate either alters the surface chemistry of lithium niobate or that there is some dipole-dipole interaction between the substrate and the zwitterion. We believe the interaction is an interface effect as no alteration in the bulk properties has been observed from spatially resolved near edge X-ray adsorption fine structure (NEXAFS) of the bulk properties. The spatial zwitterion structure is consistent with the periodically poled lithium niobate structure. Crystals of periodically poled lithium niobate (PPLN) with congruent composition (Crystal Technologies) were used as deposition templates. A periodic domain structure (period of ~28 µm) was fabricated by depositing a photoresist mask on the +c sample face and by applying a voltage of 10 kV through a fixture with an electrolyte solution. The mask was removed after poling by means of chemical-mechanical polishing leaving behind a bare ferroelectric surface, prior to the exposure to the zwitterion molecular solution.