Anomalous Surface Dynamics Near Tg in Supported Polystyrene Films by XPCS

ORAL

Abstract

The reduction of the glass transition temperature (Tg) in supported thin polymer films is of great interest. One proposed explanation is that close to the surface region there exists a thin layer with very low viscosity. Here we report a recent XPCS (X-ray photon correlation spectroscopy) measurement from silicon supported polystyrene films. At just above Tg, we have found a relaxation mode of the surface fluctuations at least 100 times faster than the capillary wave theory predicts. Surprisingly, this mode does not show significant molecular weight dependence. At higher temperatures (T-Tg$>$=50C), the surface relaxation becomes normal, as predicted by the capillary wave theory [1]. \newline \newline [1] H. Kim, et al., Phys. Rev. Lett. 90, 68302 (2003)

*This work is supported by NSF Grant DMR-0209542

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Authors

  • Zhang Jiang

    • University of California, San Diego, CA 92093
    • Department of Physics, University of California at San Diego
    • Sogang University

  • Mrinmay Mukhopadhyay

    • University of California, San Diego, CA 92093
    • Department of Physics, University of California at San Diego

  • Sunil Sinha

    • University of California, San Diego, CA 92093
    • Department of Physics, University of California, San Diego, La Jolla, CA-92093, USA.
    • Dept. of Physics, Univ. of California San Diego, La Jolla, CA 92093
    • Department of Physics, University of California at San Diego
    • University of California, San Diego
    • Department of Physics, University of California San Diego, La Jolla, CA 92093
    • University of California, San Diego and Los Alamos National Laboratory

  • Sanghoon Song

    • Dept. of Physics \& Interdisciplinary Program of Integrated Biotechnology, Sogang University, Korea
    • Department of Physics \& Interdisciplinary Program of Integrated Biotechnology, Sogang University, Korea

  • Hyunjung Kim

    • Dept. of Physics, Sogang Univ., Seoul 121-742, Korea
    • Physics \& Interdisciplinary program of Integrated Biotechnology, Sogang U., Korea
    • Department of Physics \& Interdisciplinary Program of Integrated Biotechnology, Sogang University, Korea
    • Department of Physics, Sogang University, Seoul 121-742, Korea

  • Laurence Lurio

    • Department of Physics, Northern Illinois University, DeKalb, IL-60115, USA.
    • Northern Illinois University
    • Department of Physics, Northern Illinois University