Nonmonotonic swelling of agarose-carbopol hybrid hydrogel: Experimental and theoretical analysis

A hybrid gel is synthesized by physical mixing of agarose and carbopol and an interpenetrating network of Agarose-Carbopol (AC) hybrid gel is observed by atomic force microscopy. This hybrid gel exhibits pH-responsiveness and mechanical stability as well as tunable swelling. These hydrogels depict a nonmonotonic swelling behavior as a function of pH. In particular, the equilibrium degree of swelling increases with pH of bath solution until its maximum value around pH = 7–9, followed by a decrease at higher pH values. The degree of swelling is increased by the concentration of carbopol when the concentration of agarose is low [0.25% W/V],, or decreased by the concentration of agarose when C_agarose is high [[>0:5% W/V]. A physics-based model is also adapted to characterize the swelling-shrinking behavior of different compositions of AC gels. This swelling-shrinking behavior of AC hydrogels will have potential applications in smart hydrogel-based devices.