Synthesis of Zirconia Balloon with Pores through the Crust

Abstract

Zirconia balloon with pores through the crust was synthesized by dispersing polystyrene added Zr(OC₄H₉ⁿ)₄ benzene solution to formamide. Zirconia balloon precursor was formed in F/B/F (formamide/benzene/formamide) emulsion. As benzene was extracted to formamide from the F/B/F droplets, polystyrene and Zr(OC₄H₉ⁿ)₄ phase separation occurred, and the F/B/F droplets solidified. In the balloon precursor crust polystyrene spheres dispersed in a Zr(OC₄H₉ⁿ)₄ matrix. The crust thickness was about 2 μm. The diameter of the polystyrene spheres was almost the same as the crust thickness. The spheres were removed with extraction by benzene. Spherical pores which were left in the crust opened only to the inner surface of the crust. The spherical pores were opened to the outer surface of the crust by etching the precursor balloons with hydrochloric acid. On heat-treatment at 1300°C the precursor balloons after hydrochloric acid treatment were transformed to zirconia balloons with pores through the crust. The size distribution of heat-treated balloons was in the range between 1 μm and 35 μm with a mean value of about 10 μm in diameter.