Polymer foam-reinforced hydrogels inspired by plant body frameworks as high-performance soft matter

Abstract

Plant bodies consist of many cells. Each cell contains a cell wall and a cell membrane, which are involved in maintaining the turgor pressure to bear the weight of the plant body. Inspired by this framework, we prepared a gel material enclosed in many compartments. According to this concept, hydrogels reinforced by polymer foam were fabricated using a simple method, and their mechanical properties were investigated. A piece of polymer foam was immersed in an aqueous solution of a water-soluble monomer in the presence of an initiator and a crosslinker. We used sodium acrylate as a monomer, N,N′-methylenebisacrylamide as a crosslinker, 2,2′-azobis(2-methylpropionamidine) dihydrochloride as an initiator and polyurethane foam as a reinforcing material. After gelation, the mechanical properties of the composite gel were analyzed by compression testing. The compression strength of the composite gel was ∼2 MPa, which was much higher than that of the poly(sodium acrylate) (PSA) hydrogel alone. The compression modulus was also considerably higher than for each constituent material alone (both hydrogel and foam). When melamine foam was used in place of polyurethane foam, the mechanical properties of the composite gel significantly deteriorated. We tried to prepare a gel material enclosed in many compartments, inspired by plant body framework. According to this concept, hydrogels reinforced by polymer foam were fabricated, and their mechanical properties were investigated. We prepared sodium acrylate hydrogels reinforced by open-cell polyurethane foams. After the gelation, the mechanical properties were assayed by the compression test. The compression strength of the composite gel was ∼2 MPa, which was much higher than that of poly(sodium acrylate) hydrogel alone; and the compression modulus was also considerably higher than that of each constituent material alone.