Diallylbis(3-ethoxycarbonylpropyl)ammonium chloride: A symmetrically substituted monomer for the synthesis of an alternate zwitterionic-anionic cyclopolymer

Diallylbis[(3-ethoxycarbonylpropyl)ammonium chloride] (CH₂=CHCH₂)₂N⁺[(CH₂)₃CO₂Et]₂, a new symmetrical diallyl quaternary ammonium salt, has been cyclopolymerized to its cationic polyelectrolyte (CPE) (+) I having pyrrolidine rings embedded in the polymer backbone. Polymer I would exemplify for the first time a cyclopolymer with each repeating unit bearing two identical 3-carboxypropyl pendants. (CPE) (+) I upon hydrolysis afforded pH-responsive polycationic acid (+) II, which upon successive deprotonation was transformed into a polyzwitterion acid (±) III and polyzwitterion-anion (± -) IV. Because of similar degrees of polymerization for I-IV, a meaningful comparison of their solution properties was possible. While I, II, and IV demonstrated polyelectrolyte like viscosity behavior, (±) III showed anti-polyelectrolyte properties. The anionic portion in (± -) IV controlled its solution properties. Polymer (± -) IV demonstrated remarkable antiscalant behavior; at a concentration of 15 ppm, it inhibited the precipitation of CaSO₄ from its supersaturated solution with a scale inhibition efficiency of ≈100% even after 300 min. This study opens up the possibility of using the current polymer as an antiscalant in reverse osmosis plants.[Figure not available: see fulltext.]