Transparent and flexible photocatalytic film comprising organophosphonate-modified polysilsesquioxane-anchored titanium dioxide: hydroxy group ratio and organic substituent on phosphorous atoms

Transparent and flexible photocatalytic films have attracted considerable attention in recent years. We previously prepared a film with titanium dioxide (TiO₂) and an anchor layer of phenylphosphonate-modified polysilsesquioxane (PhPPS-low), which had a phosphonate group and a phenyl substituent; this film exhibited transparency and flexibility. In this study, we reported the differences in the hydroxy group ratio on the phosphorous atoms and the presence or absence of phenylene moieties. Three organophosphonate-modified polysilsesquioxanes (APPS-low, APPS-high, and PhPPS-high) were synthesized. All photocatalytic films using APPS-high, APPS-low, and PhPPS-high exhibited photodegradation of methylene blue and photocatalytic bactericidal effects on Escherichia coli, and hydroxyl radical generation was confirmed. In particular, the photocatalytic film with PhPPS-high showed the highest photocatalytic ability.