Sorption and desorption properties of random copolymer hydrogels of N-isopropylacrylamide and N-ethylacrylamide: Effect of monomer composition

Random copolymer hydrogels of N-isopropylacrylamide and N-ethylacrylamide (NEAM) were prepared using different monomer compositions in 1:1 methanol–water mixtures. The samples were characterized by cononsolvency study in methanol-water mixtures at various temperatures, swelling properties measurements, scanning electron microscopy. With changing ratio of the monomers in the reaction mixture, the thermal, morphological and swelling properties, varied significantly. The change in the properties with monomer composition variation are interpreted based on the different thermoresponsive characteristics and interactions of gels of N-isopropylacrylamide and NEAM (homo- and copolymer gels) in water and different methanol-water mixtures, their variable compositions in the synthesis mixtures, and their morphologies.