Mesoporous materials are critical for applications such as catalyst support, energy storage and conversion, and chemical separations. Conventionally, solution based approaches are employed for the preparation of these materials, and amphiphilic molecules are widely used as templates to form well defined pore size and surface area. In these methods, the interaction between the hydrophilic block of the surfactant molecules and the metal oxide precursors direct the self-assembly of ordered micelles/metal oxide hybrid materials, and porous inorganic structures were recovered after removal of the organic template. Recently, this selective interaction was also discovered during vapor phase sequential vapor infiltration and atomic layer deposition (ALD) of metal oxide onto polymers, where precursor infusion and reaction depends strongly on the interaction between the precursor and polymer starting substrate. We therefore believe that sequential vapor infiltration or ALD on amphiphilc surfactant molecule films could also yield ordered inorganic/organic hybrid materials and porous metal oxides.

 

In this work, mesoporous aluminum oxide and titanium oxide materials were prepared by the vapor phase infiltration and ALD on two kinds of surfactants: the ionic cetyltrimethylammonium bromide (CTAB) and poly ethylene oxide based nonionic surfactant F127 (PEO-PPO-PEO). The nitrogen adsorption and desorption measurement was employed to measure the specific surface area and the pore size distribution of the resulted material. In-situ FTIR was used to monitor the chemistry change during the vapor infiltration, SEM TEM and XRD were used to characterize the structure and the morphology of the porous material.

 

We find that both sequential vapor infiltration and ALD produced mesoporous materials. However, the vapor phase infiltrated films show a relative higher specific surface area and narrower pore size distribution. This can be explained by the more uniform distribution of metal oxide into the surfactant layer compared to ALD. These results demostrate a new vapor phase approach for well defined mesoporous materials, which would potentially important for many advanced applications.