(23d) Developing Composites of Polymer Microgels and Titania Nanoparticles for Photocatalytic Degradation

Novel polymer-titania microcomposites were prepared. These composite particles were composed of titanium dioxide (TiO2) nanoparticles embedded within cross-linked, thermally responsive microgels of poly(N-isopropylacrylamide). Interpenetrating linear chains of poly(acrylic acid) were used to functionalize the nanoparticles of TiO2 for dispersal within the porous framework of the microgels. The microcomposites showed rapid sedimentation, which is useful for gravity separation of these particles in applications such as environmental remediation via photocatalytic degradation of chemical contaminants. Methyl orange was employed as a model contaminant to investigate the degradation kinetics using these microcomposites in aqueous suspensions. Kinetics of the photodegradation was evaluated by monitoring the decline in the methyl orange concentration using UV-Vis spectroscopy. Degradation of methyl orange using freely suspended titania (Degussa P25) was also conducted for comparison with the microcomposites. In this presentation, the effects stemming from different loading of TiO2 and the pH of the solution will also be discussed. These variables influence the interplay between the ionization of the poly(acrylic acid) and methyl orange, the surface charge of the titania, and adsorption of the methyl orange, which in turn determines the degradation kinetics.