Cubic polyhedral oligomeric silsesquioxane nano-cross-linked hybrid hydrogels: Synthesis, characterization, swelling and dye adsorption properties

In this study, a new series of hybrid hydrogels based on poly(N-isopropyl acrylamide-co-itaconic acid) containing octavinyl polyhedral oligomeric silsesquioxane (OV-POSS) nontoxic cross-linker with different feed ratio were fabricated via free radical copolymerization. The resulted hydrogels were characterized by FT-IR, SEM, XRD and TGA analysis. Various parameters such as time, temperature, pH and salt effects were investigated on the swelling as well as dye removal properties of hybrid hydrogels. The adsorption experiments showed that the maximum adsorption capacity accrued at pH 11 for methylene blue. Adsorption kinetics was elucidated by both pseudo-first-order and pseudo-second-order kinetic models under different conditions. Also, adsorption isotherm of the adsorption of methylene blue on poly(NIPAM-co-IA)/POSS8 adsorbent was investigated using Langmuir, Freundlich, Redlich-Peterson and Sips models, in which the experimental data were fitted well with Langmuir, model.