Swelling behavior study of poly(methacrylic acid-co-acrylamide) nanocomposite hydrogel adsorbents containing different nanoparticles

The degree of swelling can be an essential issue in comparing hydrogels in different studies. In this study, the swelling effect of hydrogel has been investigated. Poly(methacrylic acid-co-acrylamide) polymer hydrogel was synthesized by a free radical mechanism in methylene bisacrylamide as a crosslinker and potassium persulfate as an initiator. Bentonite, montmorillonite, and Cloisite 30B biodegradable clay nanoparticles were added to improve hydrogel mechanical properties and swelling speed. Fourier-transform infrared spectroscopy, X-ray diffraction (XRD), scanning electron microscopy, and thermogravimetric analysis (TGA) were used to check the structural properties. XRD analysis and TGA evaluated the mechanical properties and thermal stability. Also, it was determined from the scanning electron microscope that at the nanoscale, the distribution of clay nanoparticles among the hydrogel links was regular, and no accumulation was seen among the molecules, which indicates the continuous structure of nanocomposite hydrogels. On the other hand, TGA analysis proved the thermal stability of nanocomposites after adding clay nanoparticles. Also, the swelling rate of co-polymer and nanocomposite hydrogels was obtained by measuring the swelling rate. The desired results increased, higher than the swelling rate attributed to poly(methacrylic acid-acrylamide)/Cloisite 30B nanocomposite hydrogel. The results show that they are successful in addition to nanoparticles and increase the swelling speed of hydrogels. The analyses also show improved mechanical properties, increased surface strength and thermal stability, and optimal distribution of nanoparticles on the surface of hydrogels. The addition of clay nanoparticles to the performance of the co-polymer hydrogel increased the swelling rate up to 15 times, which can be used in the adsorption, drug delivery, and polymerization industries.