Synthetic mechanism of hydroxyapatite nanoparticles via AOT inverse microemulsions

The microemulsion solution is composed of isooctane as oil phase, sodium bis(2-ethylhexyl) sulfosuccinate (AOT) as surfactant, 1-octanol as cosurfactant, Ca(H₂PO₄)₂·H₂O solution and Ca(OH)₂ saturated solution as water phase. Hydroxyapatite nanoparticles were successfully processed by mixing the two microemulsions. The partial ternary phase diagram of microemulsions was set by a series of demarcation points between optically transparent and opaque, which indicated the single phase area of the composition and the effect of reactant ions. The diameters of inverse micellars measured by dynamic light scattering (DLS) depended linearly on water content w (w=[H₂O]/[AOT]) in case that micellars was near spherical morphology. The parameters of micellars were computed on the reactant concentration, AOT concentration and average diameter of micellars. Mechanism of reaction and particles growth showed that the reactant concentration and water content played important roles for the result particle size.