Issue 19, 2012
From the journal:

Soft Matter

Tg depression and invariant segmental dynamics in polystyrene thin films†

Virginie M. Boucher,ab   Daniele Cangialosi,*b   Huajie Yin,c   Andreas Schönhals,c   Angel Alegríabd  and  Juan Colmeneroabd  

* Corresponding authors

a Donostia International Physics Center, Paseo Manuel de Lardizabal 4, 20018 San Sebastián, Spain

b Centro de Física de Materiales (CSIC-UPV/EHU), Paseo Manuel de Lardizabal 5, 20018 San Sebastián, Spain
E-mail: swxcacad@sw.ehu.es

c BAM Federal Institute for Materials Research and Testing, Unter den Eichen 87, Berlin, Germany

d Departamento de Física de Materiales, Universidad del País Vasco (UPV/EHU), Apartado 1072, 20080 San Sebastián, Spain

Abstract

We investigate the segmental dynamics and glass transition temperature (Tg) of polystyrene (PS) thin films. The former is investigated by alternating current (AC) calorimetry and dielectric spectroscopy (BDS). The Tg, underlying the equilibrium to out-of-equilibrium crossover from the supercooled liquid to the glass, is obtained by differential scanning calorimetry (DSC) and capacitive dilatometry (CD). We show that the intrinsic molecular dynamics of PS are independent of the film thickness both for the freestanding and supported films, whereas Tg decreases with film thickness from several microns down to 15 nm. This result is found for complementary methods and in a simultaneous measurement in BDS and CD. This questions the widespread notion that segmental mobility and the equilibrium to out-of-equilibrium transition are, under any experimental conditions, fully interrelated. For thin films, it appears that the molecular mobility and Tg are affected differently by geometrical factors.

Graphical abstract: T g depression and invariant segmental dynamics in polystyrene thin films

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Article information

DOI
https://doi.org/10.1039/C2SM25419K
Article type
Communication
Submitted
23 Feb 2012
Accepted
26 Mar 2012
First published
04 Apr 2012

Soft Matter, 2012,8, 5119-5122

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T g depression and invariant segmental dynamics in polystyrene thin films

V. M. Boucher, D. Cangialosi, H. Yin, A. Schönhals, A. Alegría and J. Colmenero, Soft Matter, 2012, 8, 5119 DOI: 10.1039/C2SM25419K

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