Unique surface property of surfactant-assisted mesoporous calcium phosphate

Wormhole-like mesostructured calcium phosphates with different Ca/P molar ratios were prepared using 4-dodecyldiethylenetriamine and N-lauroyl-l-glutamic acid. Structural variations in meso- and micro-scales during calcination of the mesostructured materials were investigated by XRD, TEM and 31P MAS NMR to obtain mesoporous calcium phosphate with high surface area. Mesoporous calcium phosphate (140 m2 g−1, 0.47 cm3 g−1 and 7.1 nm) composed of calcium cations and polymorphic P units between ortho- and pyrophosphate species was obtained from the P-rich wormhole-like mesostructured product (Ca/P = 0.95). It is considered that the formation of covalent P−O−P bonds is important for the synthesis of the mesoporous calcium phosphate. A wormhole-like mesostructure of the Ca-rich calcium phosphate (Ca/P = 1.92) collapsed by calcination, because such a polymorphic change did not occur in the calcium phosphate. Adsorption properties of the P-rich mesoporous calcium phosphate were investigated by using water and cyclohexane adsorption measurements, suggesting that the calcium phosphate surfaces were extremely hydrophilic, which has not been observed for surfactant templated mesoporous materials.