Preparation of Highly Functionalized Thermoresponsive Composites Containing TiO2/Fe3O4 Nanoparticles

Highly functionalized thermoresponsive composites in which two kinds of functional inorganic particles and thermoresponsive polymer work concertedly were prepared. In this study, poly(N-isopropylacrylamide) and calcium alginate were used as the thermoresponsive polymer and structure support polymer, respectively. TiO₂ and Fe₃O₄ were used as functional inorganic nanoparticles. The thermoresponsive functional composites were prepared using a single-tube nozzle by modifying the simple process to prepare microcapsules reported in our previous study. The experimental results showed that the TiO₂/Fe₃O₄-embedded thermoresponsive composites were successfully obtained. The resulting composites exhibited thermoresponsive volume change and photocatalytic activity. Localized heating of the thermoresponsive bead containing Fe₃O₄ was also achieved by applying an alternating current (AC) magnetic field on the bead. Due to the localized heating property, repeated shrinking-swelling movement (i.e., pumping movement) of the composite was achieved by applying an AC magnetic field intermittently. Finally, based on the experimental results, the effect of the promoted mass transfer of the substrate and product due to thermoresponsive pumping on the enhancement of the apparent photocatalytic activity was simulated. The results showed the effectiveness of thermoresponsive pumping in improving the apparent photocatalytic activity of TiO₂ nanoparticles embedded in the composite gel.