Supramolecular structures in complex systems from natural and synthetic polymers. 1. Interaction between collagen, maleic polyelectrolytes and chromium ions

Supramolecular structures formed by interaction in aqueous solution between collagen as hide component and maleic acid-vinyl acetate copolymer, in the presence or absence of chromium ions were investigator by means of potentiometric, conductometric and turbidimetric titration. Depending on the concentration of collagen solution and on the concentration of the chromium ions, one-phase (homogeneous) systems or turbid dispersions were observed. The difference between turbidimetric titration and electrochemical titration showed that the interaction takes place prevalently through weak forces and to a little extent through electrostatic forces. The increase of the chromium concentration led to homogeneous systems in a broad ratio V:Col, which could be a first possibility to explain the favorable effect of V in the tanning process.