Structure and Properties of Cellulose Strengthened Poly(Acrylic Acid) Hydrogels

Abstract

Poly(acrylic acid) (PAAc) hydrogels are essential functional materials. However, their mechanical properties do not meet the required standards. In this study, a one‐pot method is employed to prepare cellulose‐reinforced PAAc hydrogels by dissolving allyl cellulose (AC) in acrylic acid (AAc) solutions. Fourier transform infrared (FTIR), solid‐state 13C nuclear magnetic resonance (NMR), and thermogravimetric (TG) analysis are used to demonstrate that the incorporation of AC results in the formation of covalent and hydrogen bonds, which contribute to the crosslink network of the PAAc hydrogels. Significantly, by modifying the ratio of AC to AAc in the pre‐polymerization solution, the prepared AC–PAAc hydrogels exhibit a transition from transparent to opaque. This suggests that phase separation is induced by hydrogen bonding. The occurrence of phase separation is verified by observing the hydrogel microstructures using scanning electron microscopy. Phase separation leads to enhanced polymer–polymer interactions in the hydrogels, resulting in a maximum fracture stress of 2.34 MPa. The AC–PAAc hydrogels display distinct swelling behavior under various pH conditions. Moreover, they demonstrate differences in transparency and mechanical properties when exposed to dimethyl sulfoxide (DMSO) and water, indicating their responsiveness to solvents. This work demonstrates the great potential of enhancing the mechanical performance and responsiveness of PAAc hydrogels.