Synthesis and application of alternate cyclopolymers of β-diallylaminoethyliminodiacetic acid with maleic acid and sulfur dioxide

Bis-cationic monomer ?-diallylaminoethyliminodiacetic acid dihydrochloride (I) underwent alternate cyclocopolymerizations with SO2 and maleic acid to give poly(bis-zwitterion) (PBZ) (? ?) II, and III, respectively. The PBZs contained the chelating motifs of [NH+(CH2)2NH+(CH2CO2- )2] embedded in the pyrrolidine ring of each repeating unit. Both the PBZs were water-insoluble, however they became water-soluble with assistance from salts like NaCl. PBZs II and III, having the point of zero charge at pH 2.4, became water soluble outside the pHwindows of 0.81?4.46 and 1.49?3.35, respectively, whereby the electroneutral pH-responsive polymers become charge-imbalanced. The ?apparent? pKas of the protonated amine centers in II were found to be 5.18 and 9.92. As an antiscalant, PBZ III (2.5 ppm) demonstrated inhibition of CaSO4 scale formation with 99% efficacy for over 180 min, while at 1.5 ppm inhibition efficiency was found to be 98% for 50 min. PBZ II at concentrations of 20 and 10 ppm demonstrated CaCO3 scale inhibition of 98% for over 240 min and 95% for over 90 min, respectively. A synergistic mixture of III (20 ppm) and KI (400 ppm) arrested corrosion of mild steel in 1 M HCl with a remarkable efficacy of 98% for 24 h at 60 ?C.

Automated summary

In this study, two water-insoluble poly(bis-zwitterion) polymers were synthesized by reacting a bis-cationic monomer with different chemical compounds and turning them into water-soluble with the assistance of salts. These polymers exhibited specific solubility properties within certain pH ranges, showing potential scale inhibition and corrosion protection effects.