Temperature-Optimized Synthesis of SiO₂-Reinforced N-(Alkyl)Acrylamide-Based Semi-IPN Hybrid Gels Functionalized with Methacrylic Acid Units

In order to obtain a pH and temperature sensitive hybrids with a controlled structure, synthesis of N-(alkyl)acrylamide-based semi-interpenetrating polymer network (semi-IPN) reinforced with silica (SiO₂) nanoparticles and functionalized with methacrylic acid units is carried out by optimizing the polymerization temperature. The study aims to understand the effect of polymerization temperature on the physical properties of semi-IPN hybrids. Changing preparation temperature between −30 and 23 °C leads to significant differences in physico-mechanical results, swelling tendency and adsorption ability, while silica nanoparticles strengthen hybrid walls, preventing their collapse during deswelling and providing rapid response. The hybrids prepared at higher temperatures are found to swell more and faster in water, while the lowest swelling is observed those prepared at 5 °C. The incorporation of SiO₂ particles into copolymer structure via physical crosslinking with network chains enhances the elasticity. The effect of polymerization temperature on adsorption is investigated using methylene blue as a model dye. Increasing polymerization temperature increases the adsorption rate and shortens time to reach the equilibrium point, and adsorption efficiency increases when polymerization temperature is lowered. The results show that semi-IPN hybrids loaded with silica nanoparticles can be used as alternative and potential adsorbents in the treatment of industrial wastes.