Eur. Phys. J. E (2005) 17: 199-202
https://doi.org/10.1140/epje/i2005-10009-7

Regular Articles

Molecular dynamics of hyperbranched polyesters in the confinement of thin films

¹ Institute for Experimental Physics I, Leipzig University, Leipzig, Germany
² Leibniz Institute of Polymer Research, Dresden, Germany
³ Institute for Physics, Rostock University, Rostock, Germany

^* e-mail: serghei@rz.uni-leipzig.de

Received: 21 January 2005
Accepted: 5 April 2005
Published online: 24 May 2005

Abstract

Broadband Dielectric Spectroscopy is employed to investigate the molecular dynamics in thin films of hyperbranched polyesters (type AB₁B₂, with -OH and -OCOCH₃ as terminal groups). Three relaxation processes are detected: alpha, beta and gamma. While the latter two are not influenced by the confinement, a pronounced effect is observed on the alpha relaxation: with decreasing film thickness the slower relaxation modes of the dynamic glass transition are gradually suppressed, resulting in an increase of the average relaxation rate and in a linear decrease of the dielectric strength. This is attributed to an immobilization in confinement of the polymeric segments located at the periphery of the hyperbranched macromolecular structures.