The ordering of semiflexible polymers with persistence length l_p and contour length L confined in a sphere of radius R is studied by molecular dynamics simulations of a coarse-grained model. Monomer densities are chosen where the corresponding bulk lyotropic solution or melt is a well-ordered nematic, and purely repulsive walls of the rigid confining sphere are considered. It is found that polymers close to the walls are bent according to the curvature of the confining spheres with all their monomers in a few layers parallel to the sphere surface, whereas the remaining macromolecules closer to the sphere center have one chain end and their center of mass far from the surface. The latter chains are responsible for the average nematic order of the system for sufficiently stiff chains. If L exceeds R, a single transition from isotropic to nematic states is found when l_p increases. However, if R is close to an even multiple of L, a second transition occurs where chain ends are enriched near the equatorial plane (and two further planes parallel to it, if R ≈ 2L); i.e., the system develops a distorted smectic structure. The order in the surface shell then is characterized by topological defects.

中文翻译：

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刚性球形胶囊中的密堆积半柔性大分子

持久性长度l _p和轮廓长度L限制在半径R的球体内的半柔性聚合物的排序通过分子动力学模拟对粗粒模型进行研究。在相应的整体溶致溶液或熔体为有序向列相的情况下，应选择单体密度，并应考虑刚性约束球体的纯排斥壁。发现靠近壁的聚合物根据约束球的曲率弯曲，所有单体在平行于球表面的几层中弯曲，而其余靠近球中心的大分子具有一个链端，且它们的中心为远离表面的质量。后面的链负责足够僵硬的链的系统的平均向列顺序。如果L超过R，则当l _p时，会出现从各向同性态向列相态的单跃迁增加。然而，如果- [R是接近的偶数倍大号，发生第二个过渡，其中链末端的赤道平面附近富集的（并平行于它两个另外的平面，如果ř ≈2大号）; 也就是说，系统发展出扭曲的近晶结构。然后，表面壳中的顺序以拓扑缺陷为特征。