Theory and small-angle neutron scattering studies of the rod-to-sphere transition of diheptanoyl-PC micelles solubilizing tributyrin

The solubilization of tributyrin by rodlike diheptanoyl-PC micelles has been studied by using small angle neutron scattering techniques. A rod to sphere transition is observed from the measured neutron scattering spectra. This transition can be explained by the formation of globular mixed micelles which have tributyrin molecules at the center surrounded by the diheptanoyl-PC molecules. When the molar ratio of tributyrin to diheptanoyl-PC is increased beyond 0.18, all the rodlike diheptanoyl-PC micelles are transformed into globular mixed micelles. The small-angle neutron scattering data were analyzed to obtain the structural parameters of these mixed micelles. They are found to grow with increasing tributyrin concentration. Theoretical explanations are given to explain the findings.