Synthesis and solution properties of an associative polymer with excellent salt-thickening

To enhance apparent viscosities in brine solutions with high salinities for associative water-soluble polymers, a novel macromonomer (APEO): allyl-capped octylphenoxy poly(ethylene oxide) (degree of polymerization: 14) was synthesized, and a novel tetra-polymer (PAVO) was synthesized by copolymerizing APEO, acrylamide (AM), sodium 2-acrylamido-2-methylpropane sulfonate (NaAMPS), and vinyl biphenyl (VP). The macromonomer and the PAVO polymer were characterized with Fourier transform infrared (FTIR) spectroscopy and proton nuclear magnetic resonance (1H-NMR). The apparent viscosities of PAVO in pure water were very low over all polymer concentrations, and the critical association concentration (C*p) was 0.15 g dL-1. However, in brine solutions above 40 g L-1 NaCl or 10 g L-1 CaCl2, the intermolecular hydrophobic associations of octylphenyl groups and biphenyl groups were enhanced dramatically, the polymer chains were still comparatively extended due to the incorporation of APEO into the polymer, C*p was reduced to 0.10 g dL-1, and the apparent viscosities were significantly higher than in pure water. The PAVO brine solutions exhibited excellent salt-thickening induced by metallic univalent or bivalent cations, heat-thickening effect, shear-thickening behavior, and thixotropy. Moreover, the brine solution also performed good resistance to ageing because of the simultaneous incorporation of bulky side groups. (C) 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012