Study on the Behavior of the Mixed Monolayer of Arachidic Acid and Cerium 2,2,6,6-tetramethylheptanedionate

The arachidic acids with Cerium 2,2,6,6-tetramethylheptanedionate were mixed at different ratios in chloroform solution and spread it onto pure water. The π-Aisotherm and the excess free energy of the mixed monolayer were studied. The miscibility, the molecular interaction of the two components and the probable condensed structure of the mixed monolayer were studied. It is found out that the Cerium 2,2,6,6-tetramethylheptanedionate/arachidic acid molar proportion of 1∶2 is the best for the formation of the stable mixed monolayer. The static elasticity and the dynamic elasticity of the mixed monolayer was also studied. It is found out that the interaction between the AA and the Ce(tmhd)4is significantly stronger and two AA molecules and one Ce(tmhd)4 molecule have formed agroup at a low surface pressure. Therefore the molecular arrangement is much closer and the mixed monolayer do not exist in the liquid state. The static elasticity and the dynamic elasticity of mixed monolayer are both enhanced especially at the low surface pressure.