Disclosed are cross-linked polymers comprising a monomer, a cross-linker, and a sulfur moiety in the polymer backbone. Methods of making cross-linked polymers comprising a monomer, a cross-linker, and a sulfur moieity in the polymer backbone are disclosed. A metal complex, comprising a cross-linked polymer chelated to a toxic heavy metal atom or ion is disclosed. The disclosure provides a method of toxic heavy metal remediation using the cross-linked polymers. Also provided are articles and coatings comprising the disclosed cross-linked polymers.