Enhancing Rheological Properties of Hydrophobically Associative Polyacrylamide Aqueous Solutions by Hybriding with Silica Nanoparticles

Organic/inorganic hybrid aqueous solutions were prepared by mixing silica nanoparticle suspension and hydrophobically associating polyacrylamide (HAPAM) solution, and their rheological behaviors were examined in both pure water and brine in comparison with HAPAM. It was found that HAPAM/silica hybrid exhibits viscosity enhancement in aqueous solution and better heat- and salt-tolerances than HAPAM. Meanwhile, their long-term thermal stability is also improved. Cryo-TEM observation reveals that a reinforced three-dimensional network structure of HAPAM/silica hybrid is formed. These improved properties are attributed to the formed hydrogen bond between carbonyl groups in HAPAM skeleton and silanol functionalities in silica nanoparticles in the hybrid system, and the silica nanoparticles in the hybrid act as physical crosslinkers between macromolecules. (C) 2014 Wiley Periodicals, Inc.