A direct quantitative measure of surface mobility in a glassy polymer.

نویسندگان

  • Y Chai
  • T Salez
  • J D McGraw
  • M Benzaquen
  • K Dalnoki-Veress
  • E Raphaël
  • J A Forrest
چکیده

Thin polymer films have striking dynamical properties that differ from their bulk counterparts. With the simple geometry of a stepped polymer film on a substrate, we probe mobility above and below the glass transition temperature Tg. Above Tg the entire film flows, whereas below Tg only the near-surface region responds to the excess interfacial energy. An analytical thin-film model for flow limited to the free surface region shows excellent agreement with sub-Tg data. The system transitions from whole-film flow to surface localized flow over a narrow temperature region near the bulk Tg. The experiments and model provide a measure of surface mobility in a simple geometry where confinement and substrate effects are negligible. This fine control of the glassy rheology is of key interest to nanolithography among numerous other applications.

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عنوان ژورنال:
  • Science

دوره 343 6174  شماره 

صفحات  -

تاریخ انتشار 2014