Effect of Ionic Strength on the Polymerization of Acrylamide, N‐Vinylpyrrolidone and Vinylbenzyl trimethylammonium chloride

Abstract Cationic polymers are promising materials for modifying the relative permeability of water in oil wells. These materials must withstand brine and temperature without losing their viscosity; one way to achieve this is by using hydrophobic groups. Some of these groups may contain a cationic part, and when polymerized, the electrostatic repulsions of the cations greatly influence the course of the reactions. In the present work, terpolymers from Acrylamide (AM), N ‐vinylpyrrolidone (VP), and Vinylbenzyl trimethylammonium chloride (VBTA) were synthesized. The effect of the ionic strength exerted by the VBTA cationic monomer and NaCl added to the reaction solution over the terpolymer synthesis was studied. Interactions between VBTA and VP were found through FTIR, 1 H‐, 13 C‐ and 15 N‐NMR, which causes inhibition of VP during the reaction. The inhibition was suppressed when using NaCl in the reaction mixture, which improved the molecular weight and the viscosity due to the suppression of the interactions between VBTA with VP. The ionic strength due to the VBTA content also influences on the properties of the terpolymers: at higher VBTA content, higher viscosity in water is obtained and present higher decomposition temperature in TGA‐DSC analysis.