理想均匀 Tetra-PEG 凝胶中聚合物的拓扑受阻动力学状态,Macromolecules

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理想均匀 Tetra-PEG 凝胶中聚合物的拓扑受阻动力学状态
Macromolecules ( IF 5.1 ) Pub Date : 2023-11-29 , DOI: 10.1021/acs.macromol.3c01745
Di Jia _{1,

2,

3} , Yui Tsuji _{1,

4} , Mitsuhiro Shibayama _{4,

5} , Murugappan Muthukumar ₁

Affiliation

当很长的聚合物被捕获到由主体水凝胶网格形成的多个熵陷阱中时，我们最近的发现表明，客体聚合物链在中间限制处被熵冻结成非扩散拓扑受挫动态状态（TFDS）。在 TFDS 的限制边界之外，客体分子扩散，而在 TFDS 范围内，由于大分子被局域化为具有极端自由能势垒的长寿命亚稳态，因此质量中心扩散系数基本上为零。大分子。然而，大分子的链段动力学是活跃的，具有层次动力学。解释 TFDS 体系中大分子的这种分层分段动力学的一个关键假设是各种熵陷阱中的单体数量是多分散的。本文通过使用理想的四聚乙二醇水凝胶作为主体基质和聚苯乙烯磺酸钠作为客体大分子实验研究链段动力学来测试该假设的有效性。我们发现，之前使用具有多分散网格尺寸分布的聚（丙烯酰胺-丙烯酸酯）水凝胶观察到的 TFDS 的所有特征在本系统中也得到了均匀网格尺寸的恢复。因此，本研究的化学细节与我们之前系统的化学细节不同，增加了 TFDS 现象普遍性的可信度。此外，目前的发现表明，各种熵陷阱中单体数量的多分散性必定是由相邻网格之间片段的局部交换动态引起的构象波动引起的。

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Topologically Frustrated Dynamical State of Polymers Trapped in Ideal Uniform Tetra-PEG Gels

When very long polymers are trapped into multiple entropic traps created by the meshes of host hydrogels, our recent discovery shows that the guest polymer chains are entropically frozen into a nondiffusive topologically frustrated dynamical state (TFDS) at intermediate confinements. Outside the confinement boundaries of the TFDS, the guest molecules diffuse, whereas in the TFDS regime, the center of mass diffusion coefficient is essentially zero due to the macromolecule being localized into long-lived metastable states with extreme free-energy barriers for the escape of the macromolecule. However, the segmental dynamics of the macromolecule is active with hierarchical dynamics. A key assumption to explain this hierarchical segmental dynamics of the macromolecule in the TFDS regime has been that the number of monomers in the various entropic traps is polydisperse. The validity of this assumption is tested in the present paper by experimentally investigating the segmental dynamics using the ideal tetra-PEG hydrogel as the host matrix and sodium poly(styrene sulfonate) as the guest macromolecule. We find that all features of TFDS previously observed using poly(acrylamide-co-acrylate) hydrogels with the polydisperse distribution of mesh size are recovered in the present system of uniform mesh size as well. Thus, the present study, with the chemical details different from those of our previous systems, adds credence to the universality of the phenomenon of TFDS. Furthermore, the present finding suggests that the polydispersity in the number of monomers in the various entropic traps must arise from conformational fluctuations emanating from the local exchange dynamics of segments among neighboring meshes.

更新日期：2023-11-29

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