IUVSTA 15th International Vacuum Congress (IVC-15), AVS 48th International Symposium (AVS-48), 11th International Conference on Solid Surfaces (ICSS-11)
    Applied Surface Analysis Wednesday Sessions
       Session AS-WeA

Paper AS-WeA9
Reconstruction of Buried Polymer Interfaces Observed by Sum-Frequency Generation

Wednesday, October 31, 2001, 4:40 pm, Room 134

Session: Depth Profiling II
Presenter: L.J. Richter, National Institute of Standards and Technology
Authors: L.J. Richter, National Institute of Standards and Technology
P.T. Wilson, National Institute of Standards and Technology
K.A. Briggman, National Institute of Standards and Technology
J.C. Stephenson, National Institute of Standards and Technology
W.E. Wallace, National Institute of Standards and Technology
Correspondent: Click to Email
The structure of polymer interfaces determines many in service properties such as adhesion. Linear vibrational spectroscopies (FTIR, ATIR, and Raman) are some of the most widely accepted and utilized diagnostics of bulk polymer systems but typically do not have sufficient specificity to probe interfaces. Vibrationally resolved sum-frequency generation (VR-SFG), a non-linear optical technique, is uniquely interface specific as it is dipole forbidden in media with inversion symmetry. We have developed a novel microcavity technique that allows selective characterization of the buried interfaces of polymer/polymer and polymer/dielectric thin film systems. We have applied the technique to the study of the buried interface between polystyrene (PS) and a hydrogen silsesquioxane (HSQ) spin-on-glass (Dow Corning FOx). The as-spun HSQ film is hydrophobic, with a water contact angle >90°. UV-ozone treatment of the as-spun HSQ results in a hydrophilic surface, with a water contact angle <10°. The structure of the PS/hydrophobic HSQ interface, as reflected in the VR-SFG spectra of the pendant phenyl groups, is very similar to that recently reported for the PS/air interface [K.A. Briggman, et al. J. Phys. Chem. B 105, 2785 (2001)]. On the hydrophilic surface, the PS 'reconstructs'. The reconstruction of the interface can be correlated with changes in the adhesion of the thin PS film to the HSQ.