Preparation of Macroporous Al2O3 by Template Method

Macroporous Al2O3 was prepared through mixing Al2O3 sol with polystyrene (PS) particles as templates, drying the suspension, and finally calcining it to remove the templates. The measurement obtained from the scanning electron microscope (SEM) showed that the formed macroporous materials had a vesicle-like structure and most of the voids left by the templates were isolated from each other. The Zeta-potential value indicated that the PS particles carried negative charges, whereas the alumina particles carried positive charges. During the preparation of macroporous Al2O3, the Al2O3 colloidal particles were adsorbed onto the surface of the PS particles, and the PS with the shell of Al2O3 particles played the role of templates, resulting in the formation of vesicle-like structures. To avoid the formation of vesicle-like structure material, the PS was switched from a negative charge to a positive charge through surface modification with PD (poly(diallyl-dimethyl ammonium chloride)) so that the PS particles carried the same kind of charges as the Al2O3 colloidal particles. The SEM images showed that the macroporous material of Al2O3, prepared using the modified PS spheres as templates, was free from the vesicle-like structure and voids left by the templates were connected through some windows.