A hybrid gel is synthesized by physical mixing of agarose and carbopol and an interpenetrating network of AgaroseCarbopol (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 Cagarose 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 swellingshrinking behavior of AC hydrogels will have potential applications in smart hydrogel-based devices. (C) 2017 Wiley Periodicals, Inc.