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Direct experimental evidences of the density variation of ultrathin polymer films with thickness

Authors :
Nicolas Delorme
Soumaya Ben Jabrallah
Joanna Giermanska
Jean-Paul Chapel
Guillaume Vignaud
Centre de Recherche Paul Pascal (CRPP)
Université de Bordeaux (UB)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)
Institut de Recherche Dupuy de Lôme (IRDL)
Université de Bretagne Sud (UBS)-Université de Brest (UBO)-École Nationale Supérieure de Techniques Avancées Bretagne (ENSTA Bretagne)-Centre National de la Recherche Scientifique (CNRS)
Institut des Molécules et Matériaux du Mans (IMMM)
Le Mans Université (UM)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)
ANR-18-CE06-0016,SISAL,Auto-Assemblage de bicouches de copolymères amphiphiles induit par une surface(2018)
Teulet, Nadine
APPEL À PROJETS GÉNÉRIQUE 2018 - Auto-Assemblage de bicouches de copolymères amphiphiles induit par une surface - - SISAL2018 - ANR-18-CE06-0016 - AAPG2018 - VALID
Source :
Polymers, Polymers, MDPI, 2021
Publication Year :
2021
Publisher :
Elsevier BV, 2021.

Abstract

International audience; Beyond the peculiar glass transition temperature (Tg) studied extensively for over two decades, we have investigated in this work the variation of the mass density of polymer thin films, a key property barely put forward in the literature. We were able to directly measure the mass density of polystyrene (PS) and poly (methyl methacrylate) (PMMA) thin films as a function of their thickness from accurate Quartz Crystal Microbalance (QCM) dissolution experiments. Depending on the chemical nature of the polymers, the results showed an unambiguous variation of the mass density when the film thickness was reduced: an increase for PS and a decrease for PMMA films. In the last part, we measured the coefficient of thermal expansion (CTE) of both polymers to rationalize the apparent inconsistency of an increase/decrease in the mass density with the commonly observed depression/rise of the Tg of PS/PMMA films. Surprisingly, the coefficient of thermal expansion and the mass density showed a similar variation with thickness, pointing out a clear correlation between the glass transition temperature, the coefficient of thermal expansion and the free volume of the polymer.

Details

ISSN :
00323861 and 20734360
Volume :
228
Database :
OpenAIRE
Journal :
Polymer
Accession number :
edsair.doi.dedup.....b517de8685ca2ee435c248fa2832fe79
Full Text :
https://doi.org/10.1016/j.polymer.2021.123934