Study on Octadecylamine Monolayer at the Air-Water Interface

By measuring the equilibrium and cyclic 1r-Aisotherms and dynamic elasticities of ocladecylamine monolayets on the subphases of water and CdGl, solution, it is showed that Cdr' added into the subphase can enhance the condensability of liquid-like monolayer but decrease that of the solid-like monolayer. On both of the subphases, the liquid-like monolayer shows reversible, while the solid-like monolayer is irreversible. This can be attributed to the hydrogen bond between ocladecylamine molecules on water and the complexation of ocladecylamine molecules with Cd2' on CdCI, subphase. In highly compressed monolayer on CdClz subphase, some metal complex comes into being and forms stable aggregate on the surface of subphase. The aggregation can also occur between octadecylamine molecules in the solid-like monolayer on pure water. The difference between the static and dynamic elasticity of the monolayer shows that dynamic oscillation with low frequency and small amplitude would weaken the complexation between octadecylamine molecules and Cd2.