Controllable speed absorbing polyacrylamide hydrogels synthesized by the method of frontal polymerization

Abstract Polyacrylamide hydrogels (PAHs) with tunable properties were synthesized via frontal polymerization (FP) in a pilot-scale reactor. The process was regulated by controlling the starting mixture’s flow rate (0.5–5 cm/min) and temperature (16 °C, 23 °C, 53 °C) under UV irradiation, while eliminating adhesion between the PAH and reactor walls. PAH characterization under specified conditions employed varied monomer ratios with natural additives. Owing to FP’s unique mechanism, water absorption capacity (1–3,500 g/g) and release of active substances were precisely controlled to meet target properties. FP-synthesized PAHs exhibited tunable water absorption rates spanning 4–96 h. Numerical calculations with 3D measurements allowed eliminating minor deviations from stationarity and nonlinearity, ensuring the reproducibility of the obtained hydrogels. No residual toxic acrylamide monomer was detected in FP-synthesized PAHs. The swelling kinetics (water absorption/release) of the resulting hydrogels were investigated, alongside their potential agricultural applications. The hydrogels demonstrated efficacy in accelerating wheat seed germination and growth.