Cu(II) immobilization in AAc/NIPAAm-based polymer systems synthesized using ionizing radiation

Polymer systems based on the pH-responsive monomer acrylic acid (AAc) and the thermosensitive monomer N-isopropylacrylamide (NIPAAm) were synthesized using gamma radiation. Three systems were synthesized: a comb-type hydrogel structure (grafting of NIPAAm onto crosslinked PAAc), a binary graft of both monomers onto a polypropylene (PP) film synthesized by a one-step method and a binary graft prepared by a two-step method. The binary graft systems were characterized by swelling behavior and the reversibility of water uptake. The three systems were compared with respect to their Cu(II) adsorption quantity, reversibility and time response. The binary graft system synthesized in one step exhibited the best adsorption response. The comb-type hydrogel required 150 h to reach its maximum swelling percentage, and the binary graft systems on polypropylene (PP) prepared by the one- and two-step irradiation-based methods required 10 and 30 min, respectively. The optimum pH range for Cu(II) immobilization was 5–6 in the binary graft system synthesized in one step. The maximum adsorption capacity for Cu(II) in the (PP-g-(AAc/NIPAAm)) (45% graft) was found to be 337 mg g−1, and the adsorption followed the Freundlich model.

► Different polymeric architectures based on AAc and NIPAAm were synthesized by gamma radiation.
► These were comb-type hydrogel of PAAc/PNIPAAm, comb-type hydrogel of PAAc/PNIPAAm grafted onto PP and binary grafting of AAc/NIPAAm onto PP.
► The last system was synthesized for the first time.
► Advantages of these systems on their swelling behavior, reversibility and velocity of response were compared in their Cu(II) immobilization.