Synthesis and characterization of polyelectrolyte brushes

On the pathway to synthesizing synthetic model systems for human cartilage, macroinitiators for the ATRP of styrene sulfonate esters with different chain lengths and initiation site densities from 10 % to 100 % were synthesized. Polymer brushes from styrene sulfonate ethyl ester and styrene sulfonate dodecyl ester with varying grafting density, backbone length and side chain length were synthesized and characterized by 1H-NMR, AUC, AFM, TEM, and in the case of the ethyl esters, GPC-MALLS. Polyelectrolyte brushes from styrene sulfonate were synthesized from the corresponding esters. These brushes were characterized in solution (GPC-MALLS, static and dynamic light scattering, SANS, 1H-NMR) and on solid interfaces (AFM and TEM). It was shown that these brushes may form extended aggregates in solution. The aggregation behavior and the size and shape of the aggregates depend on the side chain length and the degree of saponification. For samples with identical backbone and side chain length, but varying degrees of ester hydrolysis, marked differences in the aggregation behavior were observed. A functionalized ATRP macroinitiator with a positively charged head group was synthesized and employed for the synthesis of a functionalized polyelectrolyte brush. These brushes were found to form complexes with negatively charged latex particles and are thus suitable as proteoglycan models in the proteoglycan-hyaluronic acid complex.

Zylindrische Polymerbürsten aus Styrolsulfonsäureestern mit Propfdichen von 10-100% wurden über Atom Transfer Radical Polymerization (ATRP) aus bromierten Polymethylstyrol- Makroinitiatoren synthetisiert und durch NMR, AUZ, AFM, TEM und GPC-MALLS charakterisiert. Durch Verseifung wurden zylindrische Polyelektrolytbürsten aus Polystyrolsulfonat erhalten, die hinsichtlich ihres Aggregationsverhaltens mit GPC-MALLS, SLS, DLS, SANS, AFM und TEM charakterisiert wurden. Polyelektrolytbürsten mit einer positiv geladenen Kopfgruppe wurden durch Verwendung eines funktionalisierten Makroinitiators erhalten. Diese Bürsten waren in der Lage, Komplexe mit negativ geladenen Latexpartikeln zu bilden und sind somit geeignete Modelsysteme für das Proteoglykan-Molekül in Komplexen aus Proteoglykanen und Hyaluronsäure im menschlichen Knorpel.