Jörg Bohrisch

Amphiphilic cationic block copolymers via controlled free radical polymerization.

N-oxyl terminated vinylbenzyl chloride macromonomers, available via controlled free radical polymerization, were used to synthesize AB-block copolymers of vinylbenzyl chloride and styrene with low polydispersity and different block lengths and block length ratios. The vinylbenzyl chloride blocks were quantitatively converted into cationic polyelectrolytes by reactions with tertiary amines. The micellization of the synthesized amphiphilic cationic block copolymers was investigated using different techniques such as static light scattering, ultracentrifugation and size exclusion chromatography.

Characterization of synthetic polyelectrolytes by capillary electrophoresis

Capillary electrophoresis in entangled polymer solutions was applied to determine the molecular mass and polydispersity of polyelectrolytes. The separation selectivities of different polyethylene glycols as buffer additive can be correlated to their average molecular mass. A universal curve correlating the selectivity and the molecular mass could be obtained by using the instrinsic viscosity of the polyethylene glycol. The separation of poly(2-vinylpyridine) standards was compared to the separation of poly(4-vinylpyridine) standards. An indirect detection system was developed to characterize the cationic polyelectrolyte polydiallyldimethyl ammonium chloride. Various polymers with oppositely charged groups (polycarboxybetaines) were investigated with respect to structure dependence, pH dependence and molecular mass dependence of interand intramolecular association.

Electroosmotic mobility and aggregation phenomena of model polymers with permanent cationic groups

Full Paper: Capillary electrophoresis (CE) was applied to polyelectrolytes containing permanent cationic groups. The electrophoretic mobility (EM) of polycarboxybetaines at different pH strongly depends on the chemical environment of the cation. This promotes a pH dependent intra- and intermolecular aggregation. Using uncharged polymers as sieving media, the order of hydrodynamic radii superimposes the effect of number and location of the net charges on the overall mobility. EM of cationic polyelectrolytes is mainly determined by structural factors and substituent effects at the nitrogen.

Novel polyelectrolytes with regular structure-synthesis, properties and applications

A review, with 17 refs., on prepn. and properties and uses of polyelectrolytes based on poly(4-vinylpyridine) via functionalization. Cationic polyelectrolytes and polymeric betaines with narrow mol. wt. distribution and styrene block copolymers contg. charged and uncharged blocks of different hydrophilicity/hydrophobicity are described. The block copolymers are useful stabilizers in pptn. and emulsion polymn. processes. [on SciFinder (R)]