Water-soluble copolymers. XLI. Copolymers of acrylamide and sodium 3-acrylamido-3-methylbutanoate

Copolymers of acrylamide (AM, M1) with sodium 3-acrylamido-3-methylbutanoate (NaAMB, M2) synthesized in 1 M NaCl (the ABAM2 series) are compared to those synthesized in deionized water (the ABAM1 series). At fixed feed ratios, higher incorporation rates were found for NaAMB with increasing ionic strength of the polymerization solvent. Reactivity ratios calculated by the methods of Kelen-Tudos changed from r1 = 1.23 and r2 = 0.50 in deionized water to r1 = 1.00 and r2 = 0.64 in 1 M NaCl. This change is in accord with a decrease in electrostatic repulsion between the macroradical and unreacted NaAMB. Dilute solution properties, examined as a function of composition and added electrolytes, indicate differences in microstructure for the ABAMI and ABAM2 copolymers.