The ability to tailor the microstructure of porous ceramics is essential in order to fulfill the requirements of various applications. Depending on the use of porous ceramics, microstructures with open or closed pores, adjustable pore sizes, and a possible self-setting ability of the wet foam are required. We present a direct foaming method to synthesize self-setting foams with controlled microstructures, based on our previous studies on particle-stabilized foams. For the experimental set-up, alumina particles were partially hydrophobized with propyl gallate and the resulting suspensions were combined with a calcium aluminate cement reaction. Pore size and the fraction of open pores can be controlled by the particle concentration and the setting rate of the cement reaction. As a result, self-setting ceramiccement composites with porosities ranging from 40 to 95 vol% and closed as well as open pores with sizes between 30 lm and 1 mm were achieved. Compared with other methods used to produce self-setting inorganic macroporous materials, foams made with this method cover a wider pore size and porosity range and reach higher total porosities.

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Different anchoring groups have been studied with the aim of covalently binding organic linkers to the surface of alumina ceramic foams. The results suggested that a higher degree of functionalization was achieved with a pyrogallol derivative − as compared to its catechol analogue − based on the XPS analysis of the ceramic surface. The conjugation of organic ligands to the surface of these alumina materials was corroborated by DNP-MAS NMR measurements.