Synthesis, solution properties and scale-inhibiting behaviour of a diallylammonium/sulf ur dioxide cyclocopolymer bearing phospho-and sulfopropyl pendents

摘要

Zwitterion (Z) monomer 3-[diallyl{3-(diethoxyphosphoryl)propyl}ammonio]propane-1-sulfonate underwent cyclocopolymer-ization with sulfur dioxide to give a new alternating copolymer poly(Z-alt-SO2) in excellent yield (ca 90%). The polyzwitterion (±) (PZ) (i.e. poiy(Z-alt-SO2), bearing a diethylphosphonate as well as a sulfonate functionality in each repeat unit, upon ester hydrolysis gave its corresponding pH-responsive polyzwitterionic acid (±) (PZA). The pH-induced equilibrations (+) cationic polyelec-trolyte <=>(±) PZA <=> polyzwitterion/anion (± —) (PZAN) <=> polyzwitterion/dianion (± =) (PZDAN) permitted us to examine the effects of charge types and their densities on the interesting solubility and viscosity behaviours. The apparent protonation constants of the basic functionalities &tbond;N±PO_3~(2-) in (± =) PZDAN and &tbond;N±PO3H~(1-)in (± -) PZAN in salt-free water and 0.1 mol L~(-1) NaCI were determined using potentiometric titrations. (±) PZA at a meagre concentration of 20 ppm was found to be an effective antiscalant to inhibit the precipitation of CaS04 from its supersaturated solution: after 500 and 800 min, the respective scale inhibitions of 86 and 98% indicated its potential use as an effective antiscalant in reverse osmosis plant.