Berlin 2012 – scientific programme

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 33: Polymer Dynamics

CPP 33.4: Talk

Thursday, March 29, 2012, 10:30–10:45, C 264

Origin of the β-relaxation in Poly(ε-caprolactone) — •Björn Kuttich, Christina Lederle, and Bernd Stühn — TU Darmstadt, Experimentelle Physik kondensierter Materie

Broadband Dielectric Spectroscopy is a simple but highly informative measuring method to study polymer dynamics in the bulk as well as under confinement on a large timescale. By analysing the observable dielectric relaxations it is possible to investigate cooperative phenomena like the α-process and also much faster local chain dynamics.

Poly(ε-caprolactone) (PCL) is a polymer widely used in engineering and medical engineering. The latter especially because of its biodegradability. Despite of its wide application area, the basic principles of the polymer's dynamics are not yet fully understood. There are only few publications existent in which the mechanic and dielectric relaxations of PCL were investigated. Notably the reasons for the observed dielectric β-relaxation are discussed controversially.

Our experiments are now suited to clarify the reasons for the reported dielectric β-relaxation in bulk PCL. The experiments show a linear dependency of the relaxation strength of the β-relaxation from the amount of water inside the polymer. Furthermore they suggest that this relaxation is completely due to the dynamics of water molecules strongly bound to the PCL by hydrogen bonds which act as small side chains. The comparison to the dynamics of polyamides is in our view ineligible, because PCL lacks the possibility to build intra- or interchain hydrogen bonds in the absence of water molecules.