The European Physical Journal E

, Volume 20, Issue 4, pp 441–448

Molecular-weight dependence of the glass transition temperature of freely-standing poly(methyl methacrylate) films

  • C. B. Roth
  • A. Pound
  • S. W. Kamp
  • C. A. Murray
  • J. R. Dutcher
Regular Article

DOI: 10.1140/epje/i2006-10034-0

Cite this article as:
Roth, C.B., Pound, A., Kamp, S.W. et al. Eur. Phys. J. E (2006) 20: 441. doi:10.1140/epje/i2006-10034-0

Abstract.

We have used transmission ellipsometry to measure the glass transition temperature, Tg, of freely-standing films of atactic and syndiotactic poly(methyl methacrylate) (PMMA). We have prepared films with different molecular weights, MW, (159×103 < Mw < 1.3×106) and film thicknesses, h, ( 30nm < h < 200 nm). For the high-MW ( Mw > 509×103) atactic PMMA films, we find that Tg decreases linearly with decreasing h, which is qualitatively similar to previous results obtained for high-MW freely-standing polystyrene (PS) films. However, the overall magnitude of the Tg reduction is much less (by roughly a factor of three) for the high-MW freely-standing PMMA films than for freely-standing PS films of comparable MW and h. The observed differences between the freely-standing PMMA and PS film data suggest that differences in chemical structure determine the magnitude of the Tg reduction and we discuss the possible origins of these differences. Our analysis of the MW-dependence of the Tg reductions suggests that the mechanism responsible for the MW-dependent Tg reductions observed in the high-MW freely-standing films is different than that responsible for the MW-independent Tg reductions observed in the low-MW freely-standing and supported films.

PACS.

36.20.-r Macromolecules and polymer molecules 36.20.Cw Molecular weights, dispersity 64.70.Pf Glass transitions 65.40.De Thermal expansion; thermomechanical effects 

Copyright information

© EDP Sciences, Società Italiana di Fisica and Springer-Verlag 2006

Authors and Affiliations

  • C. B. Roth
    • 1
  • A. Pound
    • 1
  • S. W. Kamp
    • 1
  • C. A. Murray
    • 1
  • J. R. Dutcher
    • 1
  1. 1.Department of Physics and the Guelph-Waterloo Physics InstituteUniversity of GuelphGuelphCanada

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