Structure characterization of self-assembled monolayer film on the surface of ammonium nitrate

The effect of the self-assembled monolayer on the phase transition of ammonium nitrate was investigated the microscope morphology of the monolayer self-assemblying on the surface of ammonium nitrate was analyzed, and the interaction between the monolayer and the ammonium nitrate was understood. The monolayer self-assembling method was used to modify the surface of ammonium nitrate with surfactants. The phase transition of the modified ammonium nitrate was studied by differential scan calorimeter. The microscope morphology of the modified ammonium nitrate was observed by scanning electron microscopy. The surface structure of the modified ammonium nitrate was analyzed by virtue of X-rays photoelectron spectroscopy. The interaction between the monolayer and the ammonium nitrate was preliminary explained. The sample of ammonium nitrate modified by the system of octadecylamine and dimethyl benzene is the best one. Its hygroscopicity is only 58. 6 percents of that of the pure ammonium nitrate. The III→ IV phase transition point is 56. 00 °C for the modified sample, its is higher than that (53. 67 °C) for pure ammonium nitrate. The heat flow peak of phase II→III 0 almost disappears. The surface of ammonium nitrate particle becomes smooth and is different from the rough surface of pure ammonium nitrate. On the surface, octadecylamine interacts on cation by hydrogen bond, and CTAB interacts on nitrate anion by electrostatic force. It has much potential value to modify ammonium nitrate by monolayer self-assembling method.