This invention relates to a method of preparing a thiosulfate salt containing polymer comprising reacting at least one thiosulfate salt with at least one halogenated styrenic monomer to form a styrenic thiosulfate salt monomer represented by Formula (1); wherein X is a cationic counter ion; R1 is a substituent; and R2 is a divalent linking group; and polymerizing the styrenic thiosulfate salt monomer in the presence of an initiator.