Viscometric study of the sodium hyaluronate-sodium chloride-alkyl-(n)-ammonium surfactant system

Viscosity and rheological properties of the system sodium hyaluronate (NaHA )-NaCl-alkyl-(n)-ammonium surfactant were studied. The system with monomeri c (n = 1) surfactant dodecyltrimethylammonium bromide DTAB separated into t wo phases below the 200 mM NaCl concentration. At high NaCl concentration ( > 0.3 M), the hyaluronate-surfactant interaction is screened. At low NaCl c oncentration (0.2 M), the hyaluronate-surfactant interaction appears at hig her concentration of micelles. In the system with dimeric surfactant (n = 2 ) alkanediyl-alpha,omega-bis(dimethyldodecylammonium bromide) referred to a s 12-s-12, the hyaluronate-surfactant interaction was observed at low surfa ctant concentration, opposite to the case of NaHA-NaCl-monomeric surfactant . In certain range of surfactant concentration, viscosity of the system can be fairly good described by the empirical Jones-Dole equation. However, th e fit fails at high surfactant concentration. From the rheological measurem ents follows that NaHA aqueous solution shows non-Newtonian behaviour. When adding NaCl and shearing, viscosity increases as a result of affecting the ion atmosphere which surrounds micelles, by shearing. The same effect was observed in the system NaHA-NaCl-ammonium surfactant (both monomeric and di meric). The hyaluronate-surfactant interaction is assumed at low shearing. The influence of surfactant structure on viscosity at the same NaCl concent ration shows that the increasing value of the carbon number in spacer of di meric surfactant increases viscosity and stretches the hyaluronate coils. ( C) 1999 Elsevier Science B.V. All rights reserved.