Green synthesis of polyacrylamide/polyanionic cellulose hydrogels composited with Zr-based coordination polymer and their enhanced mechanical and adsorptive properties

As a class of typical supramolecular dynamic interactions, metal–ligand coordination has been widely used to fabricate high-performance hydrogels and coordination polymers (CPs). However, the synchronous achievement of functionalizing coordination hydrogels and shaping a stable CP through an in situ growing process in aqueous systems is still a challenge. In this paper, a series of polyacrylamide/polyanionic cellulose/Zr–CP (PAM/PAC/Zr–CP) composite hydrogels were prepared via acrylamide polymerization in aqueous solutions of PAC and disodium terephthalate (Na₂BDC), followed by posttreatment in 0.1 M ZrOCl₂ solution. The coordination of Zr(IV) clusters with carboxylates on PAC and BDC²⁻ endows the hydrogels with improved strength and adsorption of methyl orange (MO). Increasing the PAC and/or Na₂BDC amount in the precursor solution lowers the swelling ratio, tightens the network, and elevates the mechanical and MO-adsorptive properties of composite hydrogels, and the PAC dosage generates a more significant influence than the Na₂BDC concentration owing to the greater contribution of PAC to the network structures and Zr–CP states than that of BDC²⁻. Specifically, over 5 MPa of compressive strength and 500 mg MO/g Zr of MO-adsorption capacity are attained. In brief, this work provides a facile and green approach to synthesize CP-based composite hydrogels with enhanced mechanical and adsorptive properties through strong metal–ligand coordination.