PAMAM dendrimers are used as a model system to investigate the effects of counterion condensation and the effective charge for spherical polyelectrolytes. Because of their amino groups, PAMAM dendrimers are weak polyelectrolytes. Lowering the pH results in an increasing protonation of the amino groups which is monitored via the proton chemical shifts of the adjacent CH 2 groups. The effective charge is determined from a combination of diffusion and electrophoresis NMR. The fraction of the charges, which are effective for the interaction with an external electric field or other charges, decreases with increasing generation (size) of the dendrimers.

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A concept to study the influence of molecular parameters in the adsorption of polyelectrolytes is presented. Characteristic for this approach is the use of model surfaces and model polyelectrolytes. The properties of both the surfaces and polyelectrolytes can be varied in a well defined way and over a broad range. First experiments show that the method is able to give structural information about the adsorbed polyelectrolytes. The method is very sensitive, adsorption experiments with polyelectrolyte concentrations in the region of micromoles per litre are possible.

Stable polymers with nonlinear optical side groups were synthesized from maleic anhydride copolymers and the azo dye Disperse Red 1 via esterification. After electrode poling under 135 V/μm at 185 °C, thermal stabilities were measured by pyroelectric and electro-optic thermal analysis and compared to a guest/host polymer of polymethylmethacrylate and the same dye. The pyroelectrically detected dipole orientation and the electro-optic activity of the side-chain polymers decreased only above 150 °C, and electro-optic r33 coefficients of up to 6 pm/V were achieved at 780 nm even without optimizing the dye content.