Topologically Frustrated Dynamical State of Polymers Trapped in Ideal Uniform Tetra-PEG Gels
Topologically Frustrated Dynamical State of Polymers Trapped in Ideal Uniform Tetra-PEG Gels
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DOI：
10.1021/acs.macromol.3c01745
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发表时间：
2023-11
期刊：
影响因子：
5.5
通讯作者：
Di Jia;Yui Tsuji;M. Shibayama;Murugappan Muthukumar
中科院分区：
文献类型：
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作者：
Di Jia;Yui Tsuji;M. Shibayama;Murugappan Muthukumar
当很长的聚合物被困在由主机水凝胶的网格创建的多个熵陷阱中时，我们最近的发现表明，客体聚合物链在中间限制下被熵冻结成非扩散拓扑阻挫动力学状态（TFDS）。在TFDS的限制边界之外，客体分子扩散，而在TFDS制度中，质量扩散系数的中心基本上为零，这是由于大分子被定位成长寿命的亚稳态，具有用于大分子逃逸的极端自由能势垒。然而，大分子的链段动力学是活跃的，具有分级动力学。一个关键的假设来解释这种层次的链段动力学的大分子在TFDS制度一直是在各种熵陷阱的单体的数量是多分散的。本文通过实验研究了以理想的四聚乙二醇水凝胶为主体基质，聚苯乙烯磺酸钠为客体大分子的链段动力学，验证了这一假设的正确性。我们发现，所有功能的TFDS先前观察到的使用聚（丙烯酰胺-丙烯酸酯共聚物）水凝胶与网眼尺寸的多分散分布恢复在本系统的均匀网眼尺寸以及。因此，本研究的化学细节与我们以前的系统不同，增加了对TFDS现象普遍性的信任。此外，本研究结果表明，在各种熵陷阱中的单体的数量的多分散性必须产生从相邻网格之间的局部交换动态的片段所产生的构象波动。
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.