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Glass transition of polymer/single-walled carbon nanotube composite films |
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| Authors: | Joseph Q. Pham Cynthia A. Mitchell Jeffrey L. Bahr James M. Tour Ramanan Krishanamoorti Peter F. Green |
| Affiliation: | 1. Department of Chemical Engineering and Texas Materials Institute, University of Texas at Austin, Austin, Texas;2. Department of Chemical Engineering, University of Houston, Houston, Texas;3. Department of Chemistry, Rice University, MS222, Houston, Texas 77005 Department of Mechanical Engineering and Materials Science, Rice University, MS222, Houston, Texas 77005 Center for Nanoscale Science and Technology, Rice University, MS222, Houston, Texas 77005 |
| Abstract: | The glass-transition temperatures (Tg's) of nanocomposites of polystyrene (PS) and single-walled carbon nanotubes were measured in the bulk and in thin films with differential scanning calorimetry and spectroscopic ellipsometry, respectively. The bulk Tg of the nanocomposites increased by approximately 3 °C and became much broader than that of PS. For the nanocomposite films thinner than 45 nm, Tg decreased with decreasing film thickness [i.e., ΔTg(nano) < 0]. This phenomenon also occurred in thin PS films, the magnitude of the depression in PS [ΔTg(PS)] being somewhat larger. The film thickness dependence and the differences in the magnitude of ΔTg in the two systems were examined in light of current theory, and a quantitative comparison was made. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 3339–3345, 2003 |
| Keywords: | glass transition nanocomposites polystyrene thin films |