Nematic ordering of worm-like polymers near an interface.
Nematic ordering of worm-like polymers near an interface.
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DOI：
10.1063/1.5132928
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发表时间：
2020-05
期刊：
影响因子：
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通讯作者：
R. Spencer;N. Saeidi;B. Ha
中科院分区：
文献类型：
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作者：
R. Spencer;N. Saeidi;B. Ha
半柔性聚合物的相行为是从材料科学到生物物理学的各种环境中不可或缺的一部分，其中许多应用或需要特定的限制几何形状以及聚合物的取向行为。受胶原蛋白组装的启发，我们利用自洽场理论研究了半柔性聚合物的取向排序，将其建模为 Maier-Saupe 蠕虫状链。我们首先检查这些聚合物的本体行为，定位各向同性-向列相转变并描绘各向同性和向列相的稳定性极限。这项工作解释了向列相有序是如何从各向同性相中产生的，并提供了对不同（例如单域与多域）向列相如何形成的见解。然后我们阐明了平面限制对聚合物向列有序的影响。我们发现，虽然单个限制壁的存在不会改变向列相转变的位置，但它使聚合物与壁平行。在向列相转变开始以上，这种偏好倾向于传播到体相中。引入第二个垂直壁会导致向列相平行于两个壁，从而允许通过实验装置的几何形状唯一地设置排序方向。壁限制的优点是它可以用来将单域向列相传播到体相中。
The phase behavior of semi-flexible polymers is integral to various contexts, from materials science to biophysics, many of which utilize or require specific confinement geometries as well as the orientational behavior of the polymers. Inspired by collagen assembly, we study the orientational ordering of semi-flexible polymers, modeled as Maier-Saupe worm-like chains, using self-consistent field theory. We first examine the bulk behavior of these polymers, locating the isotropic-nematic transition and delineating the limit of stability of the isotropic and nematic phases. This effort explains how nematic ordering emerges from the isotropic phase and offers insight into how different (e.g., mono-domain vs multi-domain) nematic phases form. We then clarify the influence of planar confinement on the nematic ordering of the polymers. We find that while the presence of a single confining wall does not shift the location of nematic transition, it aligns the polymers in parallel to the wall; above the onset of nematic transition, this preference tends to propagate into the bulk phase. Introducing a second, perpendicular, wall leads to a nematic phase that is parallel to both walls, allowing the ordering direction to be uniquely set by the geometry of the experimental setup. The advantage of wall-confinement is that it can be used to propagate mono-domain nematic phases into the bulk phase.