Molecular dynamics of hyperbranched polyesters in the confinement of thin films.
Broadband Dielectric Spectroscopy is employed to investigate the molecular dynamics in thin films of hyperbranched polyesters (type AB(1)B(2), with -OH and -OCOCH(3) 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.
Serghei
A
A
Leipzig University, Institute for Experimental Physics I, Leipzig, Germany. serghei@rz.uni-leipzig.de
Mikhailova
Y
Y
Huth
H
H
Schick
C
C
Eichhorn
K-J
KJ
Voit
B
B
Kremer
F
F