十八胺单分子膜的研究

Study on Octadecylamine Monolayer at the Air-Water Interface

通过测定在纯水和CdCl2 溶液亚相上十八胺单分子膜的平衡、循环π～A等温线及其动态弹性 ,发现在亚相中加入Cd2 + 可以使膜的液态相凝聚性增强 ,固态相凝聚性减弱 .液态的单分子膜在两种亚相上有较好的可回复性 ,而在固态膜中则不然 .这可归因于在水面上十八胺分子间可形成氢键 ,而在CdCl2 水溶液亚相上的十八胺则与Cd2 + 发生配位 ,形成了多配位络合物 ,两种情况下十八胺分子在高膜压区都会发生稳定的聚集 .静、动态弹性的比较表明 ,膜障的振动不利于十八胺分子与Cd2 +

By measuring the equilibrium and cyclic pi similar to A isotherms and dynamic elasticities of octadecylamine monolayers on the subphases of water and CdCl2 solution, it is showed that Cd2+ 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 octadecylamine molecules on water and the complexation of octadecylamine molecules with Cd2+ on CdCl2 subphase. In highly compressed monolayer on CdCl2 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+.