Synthesis condition effects on the anti-polyelectrolyte behaviour of poly(acrylamide-co-(4-vinylpyridine)) (AM/4VP)copolymers in aqueous media

Abstract

We have synthesized new copolymers AM/4VP of acrylamide (AM) and 4-vinylpyridine (4VP) in aqueous solution by radical adiabatic copolymerization. The prepared copolymers were characterised by nuclear magnetic resonance ( 1H NMR and 13C NMR), and UV -visible spectrophotometry. The molecular weights were obtained by size exclusion chromatography (SEC), and by viscosity. The reduced viscosity variation of the copolymers aqueous solutions with its concentration showed an anti-polyelectrolyte behaviour in the presence of NaCl salt. This behaviour was explained by an increase of the reduced viscosity (ηred) in dilute system. Moreover, this phenomenon depended on synthesis conditions, such as the percentage of water and 4-vinylpyridine co-monomer in the mixture at constant values of pH and temperature.