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
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.
PACS: 61.41.+e Polymers, elastomers, and plastics – / 64.70.Pf Glass transitions – / 68.60.-p Physical properties of thin films, nonelectronic –
© EDP Sciences, Società Italiana di Fisica and Springer-Verlag, 2005
