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Article

Directly Probing Molecular Ordering at the Buried Polymer/Metal Interface

Supporting Info

Xiaolin Lu†‡, Dawei Li†‡, Cornelius B. Kristalyn‡, Jianglong Han†, Nick Shephard§, Susan Rhodes§, Gi Xue*† and Zhan Chen*‡

^† Department of Polymer Science, Nanjing University, Nanjing, People’s Republic of China 210093

^‡ Department of Chemistry, University of Michigan, 930 North University Avenue, Ann Arbor, Michigan 48109

^§ Specialty Chemicals Business, Materials Science Technology Platform, Dow Corning Corporation, 2200 W. Salzburg Road, Midland, Michigan 48686

Macromolecules, 2009, 42 (22), pp 9052–9057

DOI: 10.1021/ma901757w

Publication Date (Web): October 14, 2009

*To whom all correspondence should be addressed: e-mail xuegi@nju.edu.cn (G.X.); e-mail zhanc@umich.edu, Fax 734-647-4865 (Z.C.).

Abstract

We developed a methodology to directly probe molecular ordering at the buried polymer/metal interface. Using sum frequency generation (SFG) vibrational spectroscopy, we observed ordering of ester methyl groups at the buried poly(methyl acrylate) (PMA)/silver (Ag) interface. In order to directly probe the PMA/Ag interface, we collected SFG signal from a thin PMA film sandwiched between a fused silica substrate and a silver surface. It was found that the observed SFG signal intensity does not depend on the PMA film thickness. According to the calculated Fresnel coefficients of the fused silica/PMA and PMA/Ag interfaces with PMA films of different thicknesses, it was shown that SFG signals are solely contributed by the PMA/Ag interface. Further studies indicated that the ester methyl groups at the PMA/Ag interface tilt away from the Ag surface.

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