Effect of hydrophobic modification on the structure and rheology of aqueous and brine solutions of scleroglucan polymer

摘要

Amphiphilic scleroglucans were synthesized by grafting hydrophobic stearate groups in various densities onto the polysaccharide under its triple-helix conformation. Furthermore, a polyelectrolyte was obtained by attaching ionic-sulfonic groups to the hydrophobically modified scleroglucan. Rheological measurements demonstrated the role of grafted stearates in helix-coil transition of scleroglucan and in reducing the viscosity of scleroglucan in pure aqueous and brine solutions. Nevertheless, grafting the ionic-sulfonic groups caused a substantial recovery of the lost viscosity, especially in brine solution at 90 A degrees C, while keeping the amphiphilic character of the hydrophobically modified scleroglucan. Additionally, the hydrophobic modification altered the adsorption behavior of scleroglucan on oil-reservoir rock surfaces: the higher the grafting density, the greater the adsorption amount. However, the polyelectrolyte sample showed the lowest adsorption among all modified samples. Finally, the modified scleroglucans are promising candidates for enhanced oil recovery applications.