2023 Impact factor 1.8
Soft Matter and Biological Physics

Eur. Phys. J. E 8, 217-224 (2002)
DOI: 10.1140/epje/i2001-10088-4

Some relevant parameters affecting the glass transition of supported ultra-thin polymer films

Y. 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 $T_{\rm g}(h)$, using ellipsometry at variable temperature, for poly(methyl-methacrylate) (PMMA) of various tacticity in confined geometry. We report that several factors significantly affect $T_{\rm g}(h)$: 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 $T_{\rm g}(h)$? Does $T_{\rm g}(h)$ depend on the modifications of conformational parameters of the chains (their entropy)? What is the correlation between local dynamics and $T_{\rm g}(h)$ 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