Center for Environmental and Climate Science, Lund University, Sweden.
Soft Matter. 2023 Jul 5;19(26):4991-5000. doi: 10.1039/d3sm00373f.
The equilibrium organization of two polymers in strong confinement has been extensively investigated in the scope of simple models in the recent past, after it was suggested that the entropic repulsion between polymers could be a mechanism for chromosome separation in living cells. Despite many efforts, how solvent quality can manipulate separation or compaction for the formation of domains in a two-polymer model system within symmetric or asymmetric confinement still remains elusive. This paper presents some important findings for a two-polymer system within box-like (symmetric) and triangle-like (asymmetric) confinement with equal areas, in terms of structural transitions such as from a single globule to individual globules, non-monotonic change in polymer size, variation in the free-energy barrier with separation, By using the exact enumeration method on a two-dimensional self-avoiding walk model of polymers, our results reveal that the polymers have a greater preference to form individual globules rather than a 'micelle'-like single globule in triangular confinement compared to box-like confinement. Additionally, our results suggest that asymmetric confinement can act as an ideal tool to trap polymers in poor solvents due to the large free-energy barrier.
在过去的一段时间里，人们提出了熵斥力可能是活细胞中染色体分离的一种机制，因此，两种聚合物在强约束下的平衡组织已在简单模型的范围内得到了广泛研究。尽管已经做出了许多努力，但溶剂质量如何能够操纵分离或压缩，以在具有对称或不对称约束的两聚合物模型系统中形成域，仍然难以捉摸。本文提出了在具有相等面积的盒状（对称）和三角形（不对称）约束下的两聚合物系统中的一些重要发现，这些发现涉及结构转变，例如从单个球到单个球，聚合物尺寸的非单调变化，分离时自由能垒的变化。通过在聚合物二维自回避行走模型上使用精确枚举方法，我们的结果表明，与盒状约束相比，聚合物在三角约束下更倾向于形成单个球，而不是形成类似“胶束”的单个球。此外，我们的结果表明，不对称约束可以作为一种理想的工具，由于大的自由能垒，将聚合物困在不良溶剂中。
