Monitoring the pH change in the phase-separated hydrogel systems

This thesis pursues monitoring of pH changes and description of properties in phase–separated hydrogels prepared by interaction of polyelectrolyte and oppositely charged surfactants. For the purposes of this work, all hydrogels were prepared by the interaction of hyaluronan with Septonex. All hydrogels were exposed to pH changes (4–9). Changes in pH were being monitored using spectroscopic indicators, methyl orange, methyl red, bromothymol blue and phenolphtalein. The pre– and post– pH changes in properties were compared using rheological methods. Additional information was gathered through thermogravimetric analysis. By these methods it was proved that the changes in the pH can modify the mechanical properties and partly the internal structure of the hydrogels. Rheological tests show, that from the application point of view, the most interesting hydrogels are observed at pH 9 which have the strongest bonds but have low permeability and hydrogels described at pH 7 which are much softer and are capable of absorbing large amounts of water