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Thermal molecular motion in polystyrene thin and ultrathin films by dynamic viscoelastic measurement

  • Kei-ichi AkaboriEmail author
  • Keiji Tanaka
  • Toshihiko Nagamura
  • Atsushi Takahara
  • Tisato Kajiyama
Article

Abstract

Segmental motion in polystyrene (PS) thin and ultrathin films supported on substrates was studied by dynamic viscoelastic measurement. A polymer film, which has the thickness comparable to or less than twice of radius of gyration of an unperturbed chain (2Rg), is defined as an ultrathin film. In the case of PS, αa-relaxation process corresponding to the segmental motion was generally observed at approximately 380 K. Even for both the PS thin and ultrathin films, the αa-absorption peak was clearly observed. A rheological analysis reveals that the αa-relaxation behavior for the thin films with the thickness of about 200 nm is the same as that of the bulk sample. On the contrary, in the case of the PS ultrathin films, the αa-absorption peak on temperature-loss modulus (E) curve is broadened toward both lower and higher temperature sides. This can be interpreted by taking into account that the segmental motion in the vicinity of surface and interface is detectable for such ultrathin films, which should be faster and slower than that in the bulk, respectively. And, it is found that the apparent activation energy (ΔH) for the αa-relaxation in the ultrathin films becomes smaller than the bulk value probably due to the surface effect. Finally, an interfacial effect on the ΔH was studied by using different substrates. When the interaction between PS and substrate becomes stronger, the ΔH value for the αa-relaxation in the ultrathin films increases. The results imply that the segmental motion in the polymer ultrathin films is strongly influenced by surface and interfacial effects.

Key words

dynamic viscoelastic measurement segmental motion polymer ultrathin film polystyrene surface interface 

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References

  1. [1]
    SHUTO K, OISHI Y, KAJIYAMA T, et al. Preparetion of 2-dimensional ultra thin polystyrene film by water casting method[J]. Polymer Jounal, 1993, 25: 291–300.CrossRefGoogle Scholar
  2. [2]
    KEDDIE J L, JONES R A L, CORY R A. Size-dependent depression of the glass transition temperature in polymer films[J]. Europhysics Letters, 1994, 23: 59–64.CrossRefGoogle Scholar
  3. [3]
    KEDDIE J L, JONES R A L, CORY R A. Interface and surface effects on the glass transition temperature in thin polymer films[J]. Faraday Discusions, 1994, 98: 219–230.CrossRefGoogle Scholar
  4. [4]
    FUKAO K, MIYAMOTO Y. Glass transition temperature and dynamics of process in thin polymer films[J]. Europhysics Letters, 1999, 46: 649–654.CrossRefGoogle Scholar
  5. [5]
    MCCRUM N G, READ B E. Anelastic and Dielectric Effects in Polymeric Solid[M]. New York: Dover, 1967.Google Scholar
  6. [6]
    KAWANA S, JONES R A L. Character of the glass transition in thin supported polymer films[J]. Physical Reviw E, 2001, 63: 021501.CrossRefGoogle Scholar
  7. [7]
    TANAKA K, TAKAHARA A, KAJIYAMA T. Rheological analysis of surface relaxation process of monodisperse polystyrene films[J]. Macromolecules, 2000, 33: 7588–7593.CrossRefGoogle Scholar

Copyright information

© Central South University Press, Sole distributor outside Mainland China: Springer 2007

Authors and Affiliations

  • Kei-ichi Akabori
    • 1
    Email author
  • Keiji Tanaka
    • 1
  • Toshihiko Nagamura
    • 1
  • Atsushi Takahara
    • 2
  • Tisato Kajiyama
    • 3
  1. 1.Graduate School of EngineeringKyushu UniversityFukuokaJapan
  2. 2.Institute for Materials Chemistry and EngineeringKyushu UniversityFukuokaJapan
  3. 3.Kyushu UniversityFukuokaJapan

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