Abstract
Zwitterion (Z) monomer 3-[diallyl{3-(diethoxyphosphoryl)propyl}ammonio]propane-1-sulfonate underwent cyclocopolymerization with sulfur dioxide to give a new alternating copolymer poly(Z-alt-SO2) in excellent yield (ca 90%). The polyzwitterion (+/-) (PZ) (i.e. poly(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 polyelectrolyte reversible arrow (+/-) PZA reversible arrow polyzwitterion/anion (+/--) (PZAN) reversible arrow 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; (NPO32-)-P-+/- in (+/-=) PZDAN and & tbond; (NPO3H1-)-P-+/- in (+/--) PZAN in salt-free water and 0.1 mol L-1 NaCl 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 CaSO4 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. (C) 2014 Society of Chemical Industry