Sulfone-containing copolymers and copolymer networks and compositions including sulfone-containing copolymers and copolymer networks may be used to bind target ions, such as phosphorous-containing compounds in the gastrointestinal tract of animals. In some cases, sulfone-containing copolymers and copolymer networks may be derived from a multi- amine monomer and a multifunctional sulfonyl-containing monomer comprising two or more amine-reactive groups.