Fabrication of multifunctional poly(acrylic acid) hydrogels using a nickel–carboxymethyl cellulose crosslinker

Abstract

The derivatives of cellulose, particularly carboxymethyl cellulose (CMC), are among the popular physical crosslinkers used to improve the mechanical toughness and self-healing capability of polymeric hydrogels. In this work, we developed a multifunctional polyacrylic acid (PAA) hydrogel reinforced with CMC and nickel nanoparticles (Ni-NPs), creating a nanocomposite that combines mechanical robustness, dynamic self-repair, moderate electrical conductivity and magnetic properties. The successful incorporation of Ni-NPs in the hydrogel network was confirmed using FTIR spectra and FESEM images. TGA and DTGA studies revealed that the thermal stability of CMC was significantly improved upon the incorporation of Ni-NPs. By varying the nanoparticle content, we observed a tunable balance between mechanical strength and stretchability, with higher amounts of Ni-NPs yielding markedly enhanced tensile performance. It was found that as the amount of Ni-NPs increased, the tensile strength increased, while the elongation at the break of the hydrogel decreased. The presence of Ni-NPs also introduced reversible ionic and coordination interactions that promoted efficient self-healing. Additionally, the nanocomposite exhibited notable electrical conductivity and responsiveness to magnetic stimuli, expanding its potential functionality. All these features highlight the potential of PAA–Ni–CMC hydrogels in biomedical and soft-device applications, such as flexible sensors, tissue-interfacing materials, and magnetically controlled drug-delivery platforms, where mechanical strength, self-healing, and moderate conductivity are desirable.