Self-assembly of hydrophobic associating polyacrylamide prepared by aqueous dispersion polymerization.

Hydrophobic associating polyacrylamide (PDH) was prepared via aqueous dispersion polymerization in the presence of ammonium sulfate. In order to dissolve the polymer at high salt solution concentration, a hydrophobic precursor monomer with two cationic heads was synthesized. Upon polymerization, spherical PDH polymer particles were obtained with an average size of about 9.1 µm. The PDH was fully dispersed in water in twenty seconds, leading to a transparent gel. PDH demonstrated superior properties compared to the partially hydrolyzed polyacrylamide, for instance, regarding salt tolerance and shear resistance. Addition of a small amount of an anionic surfactant significantly affected the PDH dispersion viscosity due to the formation of mixed micelles. The viscosity slightly decreased after strong shearing (>500 s−1), showing excellent shear resistance. These features indicate that the synthesized PDH offers a great potential for application in hydraulic fracturing and enhanced oil recovery. [ABSTRACT FROM AUTHOR]