Synthesis and characterization of high performance superabsorbent hydrogels using bis[2-(methacryloyloxy)ethyl] phosphate as crosslinker

Various superabsorbent polymers (SAPs) were synthesized by free radical copolymerization at 70°C using acrylic acid (AA), potassium acrylate (KA), N-isopropyl acrylamide (NIPAM) and sulfopropyl methacrylate potassium salt (SPM) as monomers, bis[2-(methacryloyloxy)ethyl] phosphate (BMEP) as crosslinker and potassium persulfate (KPS) as initiator. The optimization of the synthesis led to the preparation of a SAP with very high water absorption ability, with a maximum swelling of 2618 g water/g dry hydrogel. The most promising SAP was fully characterized and the absorption capacities were studied at different pH and ionic strengths. When this SAP was mixed with soil, the mixture was able to lose water more slowly. Also, this material revealed high loading capacity and showed good releasing profiles using urea as model fertilizer. Due to these advantageous properties, the synthesized SAP can be used in agricultural applications.