Synthesis and Properties of Sulfonated Copolymers of Oxadiazole, Dioxophenoxathiine, and Diphenyl Oxide

Sulfonated copolymers of 1,3,4-oxadiazole, diphenyl oxide, and 10,10-dioxophenoxathiine are obtained for use as polymer superabsorbents. The one-pot synthesis of the copolymers is carried out in an oleum medium, with the starting reagents being 4,4'-oxydibenzoic acid and hydrazine sulfate. As a result, the copolymers are obtained with the same proportion of the oxadiazole fragment in the chain but different ratio of fragments containing sulfonic acid groups: diphenyl oxide fragments with two sulfonic acid groups and dioxophenoxathiine fragments with one sulfonic acid group and one sulfonyl group. The copolymers are capable of a 100-fold swelling in an aqueous medium and dissolving to a limited extent upon the addition of polar aprotic cosolvents or with an increase in pH. The ratio of sulfonic acid and sulfonyl groups in the composition of the copolymer influences its swelling in water and the viscoelasticity of hydrogels that are in the mesophase state in case of a high content of the copolymer.