Dynamics of polymer chains in ultra-thin films
Catholic University Leuven (KUL)
M ichael Wübbenhorst is professor in the Laboratory of Acoustics and Thermal Physics at the Catholic University Leuven. His
recent scientific work is largely focused on the dynamics of
polymers and complex systems studied by broadband dielectric
spectroscopy (BDRS), which involve liquid crystalline materials,
supramolecular polymers, nano-porous host-guest systems and low-k
dielectrics.
Above right: Archive photo of MW during the recent
3rd International Conference on Dielectric Spectroscopy and its
Applications (BDS 2004) held at the TU Delft in August 2004.
A persisting topic of interest is
the glass transition dynamics in simple liquids, anisotropic
(liquid crystalline) fluids and amorphous polymers, with emphasis
on the role of confinement on the cooperative dynamics. Recently,
we have implemented dielectric spectroscopy for the investigation
of ultra-thin polymer films, a technique that turned out to be
particularly beneficial due to its unmatched large dynamic range
(> 12 decades in frequency) and its increasing experimental
sensitivity (α capacitance) with decreasing film
thickness.
In PolyFilm, we will focus on the
study of the dynamics of polymer chains in grafted or spin-coated
ultra-thin polymer films by broadband dielectric spectroscopy. A
main objective is the link between conformation effects, which
are expected to occur for film thicknesses below the typical size
of the polymer random coil, and the glass transition dynamics. To
establish the relations between polymer chain configuration and
the dynamics, complementary structural investigations are
intended in close cooperation with other experimental teams from,
e.g., Lyon, Orsay, and Lorient (France).
Above left: Typical effect of thickness on the
dielectric loss spectrum ε"(f, T) for
syndiotactic PMMA showing the vanishing of the glass transition
dynamics (α-process) at a film thickness of 4 nm.
