CMC-Na and Laponite dual network reinforced P (AM-co-NVCL) hydrogel with pH/temperature dual sensitivity

Abstract

In this paper, poly (acrylamide-co-N-vinylcaprolactam) [poly(AM-co-NVCL)] hydrogels were modified by aqueous solution polymerization using sodium carboxymethyl cellulose (CMC-Na) and Laponite. Their properties were characterized by infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), X-ray diffraction (XRD), rheological testing, and scanning electron microscopy (SEM). The swelling kinetics showed that the equilibrium swelling ratio of the xerogel was influenced by the monomer ratio, crosslinking agent, and modifier content. As the Laponite and CMC-Na content increased, the compressive strength of the composite hydrogel increased, while the elongation at break decreased. The modified composite hydrogel exhibited dual sensitivity to pH and temperature. DSC and rheological tests indicated that CMC-Na functioned as a physical crosslinking agent in the system, and with the increase in CMC-Na content, the crosslinking effect was enhanced. SEM demonstrated that the addition of Laponite and CMC-Na increased the number of pores in the hydrogel and decreased the pore size.