Chemical Synthesis of Microskeletal Calcium Phosphate in Bicontinuous Microemulsions

Supersaturated bicontinuous microemulsions have been used as organized reaction environments for the chemical synthesis of calcium phosphates with interconnected microskeletal architectures. Nucleation of apatite occurs within the nanometer-size water conduits of oil/water microemulsions stabilized with didodecyldimethylammonium bromide (DDAB). Subsequent growth results in localized microstructural changes such that the crystals attain dimensions that are larger than the microemulsion channels. Changes in the composition and texture of the microemulsions result in significant modifications in the inorganic architectures. Reticulated inorganic materials are formed from bicontinuous microemulsions that contain a liquid aqueous phase when stored at temperatures below the melting point of the oil phase (dodecane, tetradecane, or tetradecane/hexadecane). Similar experiments with DDAB microemulsions prepared as the high water containing cubic phase or with compositions close to edge of the bicontinuous phase boundary did not produce meshwork architectures. Calcium phosphates grown in tetradecane/water microemulsions stabilized with pentaethylene glycol dodecyl ether had an unusual sheetlike form.