Cyclopolymerization protocol for the synthesis of a new poly(electrolyte-zwitterion) containing quaternary nitrogen, carboxylate, and sulfonate functionalities

A new zwitterionic monomer, N-carboethoxymethyl-3-(N,N-diallylamino)propanesulfonate, on cyclopolymerization in aqueous solution using tert-butyl hydroperoxide, afforded a polyzwitterion (PZ) which on acidic hydrolysis of the ester groups led to the corresponding polyzwitterionic acid (PZA). The pH-responsive PZA on treatment with sodium hydroxide gave a new poly(eletrolyte-zwitterion) (PEZ) in excellent yield. The solution properties of the salt-tolerant PZ, PZA and PEZ were studied in some detail. Unlike common polyzwitterions, PZ and PZA were found to be soluble in salt-free as well as salt-added water. The apparent basicity constants of the carboxyl group in PEZ have been determined in salt-free water and 0.1 M NaCl. The poly(electrolyte-zwitterion) (PEZ), as the name implies, possesses dual type of structural character common to both conventional anionic polyelectrolytes and polyzwitterions, and its aqueous solution behavior is found to be similar to that observed for a typical alternating anionic–zwitterionic copolymer.