Logo JG-Universität MainzProf. Dr. Axel Müller


Felix A. PlamperDr.

Felix A. Plamper

PhD student

At Macromolekulare Chemie II until 07/2007
e-Mail: plamper(at)pc.rwth-aachen.de

RWTH Aachen

Lehrstuhl für Physikalische Chemie II,
Institut für Physikalische Chemie
RWTH Aachen
Landoltweg 2
52056 Aachen

Tel: 0241-8098613
Fax: 0241-8092327

Research Interests:

The behaviour of macromolecules depends on the molecular architecture.

Plamper, Felix - Fig.1 Detailansicht

Fig. 1: different branched polymer architectures

So show branched polymers reduced viscosity in solution and in melt due to decreased dimensions compared to the linear analogues. Often the solubility changes, which can be assigned to a higher number of chain ends. Those can be solubilized in a different manner compared to the repeating unit of the polymer. These are just two examples how one can combine altered physical response with the same chemical building block (repeating unit of the polymer). Branched polymers are even able to give new physical properties unknown for their linear analogues. So can polymers with star-shaped geometry behave like soft spheres. These exert a radial pair potential with ultrasoft interaction, which leads to ordered, crystalline phases in solution1. These were predicted and experimentally proven for uncharged polymer stars. Only theoretical work was done so far on polyelectrolyte stars (charged polymer stars), which also promise rich phase behaviour2.

Plamper, Felix Fig. 2 Detailansicht
Fig 2: polyelectrolyte star; picture taken from Jusufi et al3

Plamper, Felix - Fig. 3
Fig 3: Phase behaviour of polyelectrolyte stars in dependence
of concentration (x axis) and arm number f (taken from Jusifi et. al)2

My task is to synthesize and characterize appropriate polyelectrolyte stars on basis of poly(acrylic acid) and prove the existence of theses phases experimentally. These phases may be interesting for future applications as optical grids in water (stars labelled with fluorescence dye). Before we want to examine the phase behaviour, we want to determine the solution properties in the diluted regime. Branching alters for example neutralization. The higher the branching the less are protons accessible to base. Furthermore the majority of counterions are confined within the stars, so that the overall charge of the stars is rather low. This counterion confinement shall be measured with different techniques like osmometry, activity measurements (both count free ions), Small Angle X-Ray Scattering (gives the distribution of counterions) and self diffusion experiments (resolves fractions of ions with different mobility) and electrophoresis (gives the overall charge). Small Angle X-Ray Scattering will also play a crucial part in discovering the ordered phases in solution. Finally I am not only interested in star-shaped architecture but also in brush-like geometry. Especially cylindrical brushes may for example be used in future as templates for nanowires. Therefore I develop new strategies to obtain brushes for special monomers like vinylacetate.

(1) Likos, C. N.; Löwen, H.; Watzlawek, M.; Abbas, B.; Jucknischke, O.; Allgaier, J.; Richter, D. Phys. Rev. Lett. 1998, 80, 4450.
(2) Likos, C. N.; Hoffmann, N.; Jusufi, A.; Löwen, H. J. Phys.: Condens. Matter 2003, 15, 233.
(3) Jusufi, A.; Likos, C. N.; Löwen, H. Journal of Chemical Physics 2002, 116, 11011-11027.

>> Publications
>> PhD Thesis

powered by php + PostgreSQL - last modified 2009-08-26- Impressum