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Updated: May 18, 2026

Fabrication of Large-area Free-standing Ultrathin Polymer Films
10:08

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Published on: June 3, 2015

Structural relaxations of thin polymer films.

Bradley Frieberg1, Emmanouil Glynos, Peter F Green

  • 1Macromolecular Science and Engineering Program, University of Michigan, Ann Arbor, Michigan 48109, USA.

Physical Review Letters
|September 26, 2012
PubMed
Summary

Physical aging in star-shaped macromolecule films depends on arm number and length. Interface regions age differently than the bulk, explained by local glass transition temperature changes.

Area of Science:

  • Materials Science
  • Polymer Physics
  • Physical Chemistry

Background:

  • Glasses exhibit time-dependent changes in thermodynamic properties due to structural relaxations and physical aging.
  • Physical aging affects the properties of materials over time, influenced by molecular structure and environmental factors.

Purpose of the Study:

  • To investigate the physical aging dynamics of thin supported films of star-shaped macromolecules.
  • To determine the influence of molecular architecture (number of arms 'f' and arm length 'N(arm)') on aging behavior.
  • To understand the role of interfaces in the aging process of these films.

Main Methods:

  • Studied thin supported films of star-shaped macromolecules.
  • Analyzed aging dynamics as a function of molecular parameters (f and N(arm)).

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  • Compared aging rates in film regions near interfaces versus the bulk interior.

    • Main Results:

    • Aging dynamics of star-shaped macromolecule films are sensitive to the number of arms (f) and arm length (N(arm)).
    • Regions of the film near interfaces exhibit significantly different aging rates compared to the film's interior.
    • This interfacial effect on aging is also observed in linear polymer systems.

    Conclusions:

    • A universal model reconciling aging differences can be based on local changes in the glass transition temperature (T(g)).
    • The local T(g) provides a unifying explanation for varied aging rates observed in different regions of the films.
    • Understanding these aging dynamics is crucial for applications involving thin polymer films.