Morphology transition and slow dynamics in the collapse of amphiphilic monolayers at the air-water interface
Morphology transition and slow dynamics in the collapse of amphiphilic monolayers at the air-water interface
复制标题
空气-水界面两亲单层塌陷的形态转变和缓慢动力学
DOI：
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发表时间：
1999
期刊：
影响因子：
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通讯作者：
J. Nagao
中科院分区：
文献类型：
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作者：
E. Hatta;D. Suzuki;J. Nagao
用相衬显微镜研究了空气-水界面上坍塌的单层膜的形貌。研究发现，随机分布裂纹模式向准一维裂纹模式的转变取决于亚相的pH值和特定二价金属离子的存在。在这些宏观模式中，前者由于单层屈曲而表现出表面粗糙，而后者则变得更加光滑和均匀。前者的发生是瞬时的，后者的发生是一个缓慢的动力学过程，即裂纹在单层中的扩展伴随着裂纹成核的延迟。因此，这种格局的变化表明了一种动态转变的存在。在脆性材料的裂纹失稳情况下讨论了这种转变。黏性、离子结合和压缩方向的变化可能对观察到的行为起了有效的作用。
The morphology on collapsed monolayers at the air-water interface has been studied using phase contrast microscopy. It is found that the transition from randomly distributed to quasi-one dimensional crack pattern takes place, depending on the pH value of the subphase and the presence of specific divalent metal ions. In these macroscopic patterns, the former exhibits a surface roughening due to a monolayer buckling while the latter becomes more smooth and uniform. The occurrence of the former is instantaneous and the latter follows a slow dynamics, i.e., the crack propagation in monolayers occurs with a delay for crack nucleation. Thus the change of pattern indicates the existence of a dynamic transition. The transition is discussed with the scenario of a crack instability in brittle materials. The changes of viscous nature and of ion binding, and the compression direction probably operate for the observed behavior effectively.