Evaluation of porosity of polymer-templated TiO₂ nano-thin films: Selective adsorption of C₆₀ fullerene and cytochrome c

TiO₂/polymer nano-thin films that were assembled with a polymer (polyacrylic acid, PAA or polyvinyl alcohol, PVA) and Ti(O-"Bu)₄ by the surface sol-gel process. These films were employed for fabrication of nanoporous TiO₂ thin films. The template polymers of PAA and PVA were removed by plasma treatment and polymer-templated nanocavities in the TiO ₂ films were prepared. The pore size of the nanocavities was approximately estimated by the adsorption of C₆₀ and Cyt. c, which have a specific molecular size of 1 nm and 3 nm, respectively. The PVA templated-TiO₂ film showed an improved adsorption of C₆₀ and Cyt. c after plasma treatment, which increased in proportion to the number of deposition cycles. Consequently, it was evident that the PVA templated-TiO₂ film has pores larger than 3 nm, whereas pores smaller than 1 nm were prepared in the PAA templated-TiO₂ film.