Robust, recoverable poly(N,N-dimethylacrylamide)-based hydrogels crosslinked by vinylated chitosan with recyclable adsorbability for acid red

To seek adsorptive hydrogels with high stability, poly(N,N-dimethylacrylamide) (PDMAM)-based hydrogels were fabricated employing vinylated chitosan as a macro-crosslinker. The prepared hydrogels achieves a maximum compressive stress above 11 MPa (98% strain), a maximum tensile strength, and fracture elongation of 0.037 MPa and 929%. The recovery ratios after three consecutive compressions (90% strain) and 1 h's resting (600% stretch) exceed 94% and 85%, respectively. The optimal adsorption effect (>90% removal efficiency) is achieved at pH 3 and 318 K in 2.5 h using hydrogels crosslinked by 9.77 wt % chitosan. The kinetic study indicates that the experimental data fit to the pseudo-second-order kinetic model better. The adsorption isotherm fits to the Freundlich model, indicating nonhomogeneous adsorption of the dyes on the hydrogels. Most adsorbed dyes are desorbed in 2 h at pH 10 and 318 K, both adsorption/desorption efficiencies exceed 90% after five adsorption–desorption cycles, confirming reusability of the hydrogels. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136 , 47473.