Scope of sulfur dioxide incorporation into alkyldiallylamine–maleic acid–SO(2) tercyclopolymer

Alternate copolymerization of diallylamine derivatives [(CH(2)CH[double bond, length as m-dash]CH(2))(2)NR; R = Me, (CH(2))(3)PO(OEt)(2), and CH(2)PO(OEt)(2)] (I)–maleic acid (MA) and (I·HCl)–SO(2) pairs have been carried out thermally using ammonium persulfate initiator as well as UV radiation at a λ of 365 nm. The reactivity ratios of ≈0 for the monomers in each pair I–MA and I·HCl–SO(2) ensured their alternation in each copolymer. However, numerous attempted terpolymerizations of I–MA–SO(2) failed to entice MA to participate to any meaningful extent. In contrast to reported literature, only 1–2 mol% of MA was incorporated into the polymer chain mainly consisting of poly(I-alt-SO(2)). Quaternary diallyldialkylammonium chloride [(CH(2)[double bond, length as m-dash]CH–CH(2))(2)N(+)R(2)Cl(−); R = Me, Et] (II) also, did not participate in II–MA–SO(2) terpolymerizations. Poly((I, R = Me)-alt-SO(2)) III is a stimuli-responsive polyampholyte; its transformation under pH-induced changes to cationic, polyampholyte-anionic, and dianionic polyelectrolytes has been examined by viscosity measurements. The pK(a) of two carboxylic acid groups and NH(+) in III has been determined to be 2.62, 5.59, and 10.1. PA III, evaluated as a potential antiscalant in reverse osmosis plants, at the concentrations of 5 and 20 ppm, imparted ≈100% efficiency for CaSO(4) scale inhibition from its supersaturated solution for over 50 and 500 min, respectively, at 40 °C. The synthesis of PA III in excellent yields from cheap starting materials and its very impressive performance may grant PA III a prestigious place as an environment-friendly phosphate-free antiscalant.