The effect of surfactant type and concentration on the pore structure of alumina aerogels

Alumina aerogels are excellent materials for thermal insulators used at high temperatures due to the good thermal stability of aluminum oxide. In this study, alumina aerogels treated with various types of surfactants (non-ionic (Triton X-100), cationic (cetyltrimethylammonium bromide), or anionic (sodium dodecyl sulfate)). The effect of the surfactant depended on the charge-charge interactions between it and the cationic inorganic species in the aluminum precursor. As determined by using small-angle scattering and pore volume change measurements, these interactions induced a change in the pore structure that could be controlled by controlling the concentration of the surfactant. The hindrance effect due to the ionic interference was more pronounced at a higher surfactant concentration than at a lower one. Thus, the concentration of surfactant plays an important role in determining the pore structure of the alumina aerogel.