The poly(zwitterion-alt-sulfur dioxide) copolymer includes a structural unit having the structural formula: wherein “n” is the number of repeating units. The copolymer is made by cocyclopolymerizing 3-(N,N-diallyl,N-carboethoxymethylammonio)propanesulfonate with sulfur dioxide to obtain an intermediate polyzwitterion (PZ) copolymer, which is hydrolyzed to form the copolymer. The copolymer may be converted to a poly(electrolyte-zwitterion) by treatment with a base, such as sodium hydroxide.