Interfacial instability and spontaneous formation of microemulsions
Interfacial instability and spontaneous formation of microemulsions
复制标题
界面不稳定性和微乳液的自发形成
DOI：
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发表时间：
1972
期刊：
影响因子：
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通讯作者：
R. Walker
中科院分区：
文献类型：
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作者：
D. Shah;A. Tamjeedi;J. Falco;R. Walker
微乳液是一种光学透明的油水分散体，在十六烷、己醇、油酸钾和水按特定比例混合后自然产生。在己醇或油酸钾存在的情况下，十六烷-水界面的滴体积测量表明，这些表面活性剂降低了十六烷-水界面的族间张力。提出这两种乳化剂在油水界面的相互作用引起自发的负界面张力，导致界面不稳定并形成微乳液。
Microemulsions, which are optically transparent oil-water dispersions, were spontaneously produced upon mixing hexadecane, hexanol, potassium oleate, and water in specific proportions. The drop-volume measurements of hexadecane-water interface in the presence of hexanol or potassium oleate revealed that these surfactants decrease the interracial tension of the hexadecane/water interface. It is proposed that the interaction between these two emulsifiers at the oil-water interface causes spontaneous negative interfaical tension resulting in interfacial instability and the formation of microemulsions.
As the amount of water is increased, the microemulsion exhibits a clear to turbid to clear transition. Unlike the clear regions, the turbid region possesses birefringence. The development of birefringence is also accompanied by a sharp decrease in electrical resistance. High-resolution (220 Mc) nuclear magnetic resonance data suggest that water exists in two distinct environments or structures in the birefringent region. The electrical, birefringence, and nuclear magnetic resonance data agree with the proposed mechanism of phase-inversion of microemulsions, which can be described as water spheres to water cylinders to water lamellae to a continuous water phase. The spontaneous formation of such structures (for example, water cylinders and lamellae) presumably depends upon the phase-volume ratio and the interfacial tension at the oil-water interface.