Synthesis and rheological properties of amphoteric hydrophobically associating polymer P(AM/AA/AMPS/C₁₈DMAAC)

An amphoteric hydrophobically associating polymer (AHAPAM) was prepared by inverse emulsion polymerization of acrylamide (AM), acrylic acid (AA), 2-acrylamide-2 methyl propane sulfonic acid (AMPS), and N, N-dimethyl octadeyl allyl ammonium chloride (C18DMAAC). The microstructure was studied by FTIR, 1H-NMR and SEM. The effects of mass fraction of hydrophobically associating polymers and NaCl content on the apparent viscosity of the polymer solution were studied by Brookfield viscometer and rheology. FTIR and 1H-NMR spectra proved that the hydrophobic monomer was successfully introduced to the polymer molecular chains. A turning point of apparent viscosity was revealed with the increase of polymer concentration, and the critical association concentration of the AHAPAM solution was found to be 0.15 wt%. The addition of NaCl shields the electrostatic interaction between the cation and anion groups, proving AHAPAM processed good salt tolerance. Moreover, the rheological analysis evidenced the elastic nature of AHAPAM solution.