(17e) PREPARATION of THERMO-RESPONSIVE FUNCTIONAL COMPOSITES by EMBEDDING TiO2/Fe3O4 NANOPARTICLES

Thermo-responsive functional composites were prepared by embedding two kinds of functional inorganic particles within thermo-responsive microgel. In this study, poly(N-isopropylacrylamide) was used as thermo-responsive polymer, calcium alginate was used as structure support polymer and TiO₂ and Fe₃O₄ were used as functional inorganic nanoparticles respectively. In the experiment, thermo-responsive functional composites were prepared using single tube nozzle by modifying the simple process to prepare thermo-responsive capsule reported in our previous report¹⁾.  In the process, two solutions were prepared such as a polymer solution and a solution for gelation reaction. In the polymer solution, NIPAM monomer, sodium alginate and a cross-linker agent were dissolved. TiO₂ and/or Fe₃O₄ were also dispersed in the polymer solution. The solution for gelation reaction was prepared by dissolving a gelation agent, a polymerization initiator and an polymerization accelerator into a buffer solution. When the droplets of the polymer solution containing functional particles were dripped into the solution for gelation reaction, gelation of alginate and polymerization of NIPAM and the cross-linker were occurred at the same time and gel beads with interpenetrating polymer network (IPN) structure were obtained instantaneously. The characterization was carried out by examining their thermo-responsive property, photocatalytic activity and localized heating property. The experimental results showed that TiO₂/Fe₃O₄ embedded microgels were obtained successfully. The obtained beads exhibited thermo-responsive volume change and photocatalytic activity.  Localized heating of one thermo-responsive bead containing Fe₃O₄ was also achieved without raising a bulk solution temperature by focusing laser irradiation on the bead.