Glass transition behavior of polymer films of nanoscopic dimensions

Arlette R.C. Baljon, Maarten H.M. Van Weert, Regina Barber Degraaff, Rajesh Khare

Research output: Contribution to journalArticlepeer-review

56 Scopus citations

Abstract

Glass transition behavior of nanoscopically thin polymer films is investigated by means of molecular dynamics simulations. We study thin polymer films composed of bead-spring model chains and supported on an idealized fee lattice substrate surface. The impact on the glass transition temperature of the strength of polymer-surface interaction and of chain grafting to the surface is investigated. Three different methods-volumetric, energetic, and dynamic-are used to determine the glass transition temperature of the films. On the basis of these, we are able to identify two different transition temperatures. When the temperature is lowered, a first transition occurs that is characterized by an anomaly in the heat capacity. Upon decreasing the temperature further, a point is reached at which the internal relaxation times diverge, as calculated, using for instance, the mode coupling theory. In qualitative agreement with the experiments, the former temperature depends on the characteristics of the polymer-surface interaction. By contrast, the latter temperature is independent of these.

Original languageEnglish
Pages (from-to)2391-2399
Number of pages9
JournalMacromolecules
Volume38
Issue number6
DOIs
StatePublished - Mar 22 2005

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