Lattice model of mobility at interfaces: free surfaces, substrates, and bilayers
Lattice model of mobility at interfaces: free surfaces, substrates, and bilayers
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界面迁移率的晶格模型：自由表面、基底和双层
DOI：
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发表时间：
2013
期刊：
影响因子：
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通讯作者：
S. Milner
中科院分区：
文献类型：
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作者：
N. Tito;J. Lipson;S. Milner
一个简单的动力学晶格模型的自由体积和流动性输运的流体被施加到研究流动性的增强在一个自由表面的薄流体膜，以及邻近效应的流体双层材料组成的不同的本地流动性。与流体和聚合物薄膜的实验观察一致，我们的模型预测存在一个移动的层的材料附近的自由表面的动力学逮捕（玻璃）膜。当样品接近完全流动性的转变时，移动的层以类似于前的方式更深地延伸到膜中。在给定的温度下，增强的迁移率的程度是独立的膜厚度，因此，我们发现，较薄的膜具有更多的抑制样品平均玻璃化转变温度相比，散装材料。这一主题在我们对流体双层的模拟中重复出现;分别具有抑制或增强流动性的材料板导致整个系统过早或延迟玻璃化。
A simple kinetic lattice model of free volume and mobility transport in fluids is applied to study the enhancement of mobility at a free surface in thin fluid films, as well as proximity effects in fluid bilayers consisting of materials with different local mobility. Consistent with experimental observations on fluid and polymeric thin films, our model predicts the presence of a mobile layer of material near the free surface of a kinetically arrested (glassy) film. The mobile layer extends deeper into the film, in front-like fashion, as the sample approaches the transition to complete fluidity. The extent of enhanced mobility is independent of film thickness at a given temperature, thus we find that thinner films have more suppressed sample-average glass transition temperatures compared to bulk material. This theme repeats itself in our simulations of fluid bilayers; slabs of material with suppressed or enhanced mobility respectively cause premature or delayed glassification of the whole system.