Surfactant based assembly of mesoporous patterned calcium phosphate micron-sized rods

The synthesis of mesostructured calcium phosphate micron-sized rods and nanoparticles using mono-n-dodecyl phosphate ((C12H25O)P(O)(OH)2, MDP) and cetyltrimethylammonium bromide (C19H42BrN, CTAB), is described. The effect of concentration, molar ratio, and ethanol as co-solvent on the shape, size, and porous structure of the resulting materials is discussed. MDP was used as a surfactant to pattern the rods with pores generated by the formation of a lamellar calcium MDP phase. CTAB, as a co-surfactant could be used to form micron-sized rods of varying length based on its molar ratio with the other reactants. Ethanol affected surfactant self-assembly, and could be used to change particle morphology from sphere-like to fiber. Certain synthesis conditions yielded low surface area spherical brushite nanoparticles grown from 46 nm MDP vesicles, while others resulted in micron-sized rods with surface areas of 90 m2/g and a porosity of 30% comprised primarily of octacalcium phosphate.