Viscosity Behavior and Associated Morphologies of a Branched Acrylamide-Based Terpolymer in Water and Brine Solutions

A water-soluble terpolymer, PAAB, was copolymerized using acrylamide (AM), sodium 2-acrylamido-2-methylpropane-sulphonate (NaAMPS), and a novel macro-monomer, p-vinylbenzyl-terminated octylphenoxy poly(ethylene oxide) (VBE, polymerization degree: 24). This polymer exhibited associating effect and good thickening properties in unsalted and brine solutions, and the effect of salt on apparent viscosity was much weaker than that of the linear associating polymers only containing small hydrophobic monomers. Its brine solution exhibited salt-thickening behavior twice and good resistances to heat because of the incorporation of the functional poly(ethylene oxide) side chains. The PAAB aqueous and brine solutions also displayed obvious shear thickening behavior upon repetitious three-shear cycles. It was found by a scanning electron microscope (SEM) that the polymer chains were extended and large associated structures were formed in brine solutions as well as in water at the PAAB concentrations of 0.05-0.15g/dL.