Eur. Phys. J. E 8, 217-224 (2002)
Some relevant parameters affecting the glass transition of supported ultra-thin polymer filmsY. Grohens1, L. Hamon2, G. Reiter2, A. Soldera3 and Y. Holl4
1 Laboratoire Polymères et Procédés, Université de Bretagne Sud, Rue St. Maudé, BP 92116, 56325 Lorient Cedex, France
2 Institut de Chimie des Surfaces et Interfaces, 15 Rue J. Starcky, BP 2488, 68057 Mulhouse, France
3 Université de Sherbrooke, Faculté des Sciences, Département de Chimie, Sherbrooke, J1K2R1, Canada
4 Institut Charles Sadron, 6 rue Boussingault, 67083 Strasbourg Cedex, France
(Received 4 October 2001 and Received in final form 14 February 2002)
We have measured, the thickness dependence of the glass transition temperature , using ellipsometry at variable temperature, for poly(methyl-methacrylate) (PMMA) of various tacticity in confined geometry. We report that several factors significantly affect : i) polymer microstructure (stereoregularity of PMMA) related to local dynamics; ii) interfacial interactions; iii) conformation of the polymer chains. These results raise many fundamental questions on the origin of the thickness-dependent glass transition. Why and how do the interactions with the substrate significantly affect ? Does depend on the modifications of conformational parameters of the chains (their entropy)? What is the correlation between local dynamics and in thin films? The aim of this paper is to summarise these open questions, which should stimulate further investigations in the thin polymer film scientific community.
64.70.Pf - Glass transitions.
61.41.+e - Polymers, elastomers, and plastics.
68.60.-p - Physical properties of thin films, nonelectronic.
61.20.-p - Structure of liquids.
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag 2002