Sticky Rouse Time Features the Self-Adhesion of Supramolecular Polymer Networks
Sticky Rouse Time Features the Self-Adhesion of Supramolecular Polymer Networks
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DOI：
10.1021/acs.macromol.1c00335
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发表时间：
2021-05
期刊：
影响因子：
5.5
通讯作者：
Zhiqiang Shen;Huilin Ye;Qiming Wang;M. Kröger;Ying Li
中科院分区：
文献类型：
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作者：
Zhiqiang Shen;Huilin Ye;Qiming Wang;M. Kröger;Ying Li
超分子聚合物是一种令人着迷的材料，因为它们具有可逆键赋予的惊人的自修复能力。然而，由于缺乏对断裂界面分子结构演化的了解，没有现有的理论来解释和预测实验中观察到的不同超分子材料的不同愈合时间。在这里，我们通过分子模拟系统地研究了非缠结和缠结超分子聚合物网络的自粘附。我们发现宏观界面强度的恢复几乎线性取决于超分子聚合物断裂界面处的微观分子形成，包括可逆键和缠结（仅限缠结系统）。更重要的是，我们将愈合时间置于超分子聚合物网络的固有弛豫时间尺度的背景下。研究发现，本征粘性劳斯时间表征了所有断裂超分子聚合物的自粘附过程，代表了界面强度的完全恢复。在这个关键的时间尺度上，发生了两件事来保证断裂系统的完全恢复：（i）聚合物链以与其尺寸相当的位移扩散穿过断裂界面； (ii) 交叉的贴纸和聚合物链分别更新了它们的可逆键和缠结（仅限缠结系统）。清晰的分子描述和建议的特征自粘附时间将有助于超分子聚合物的分子设计。 ■ 简介 为了模仿人类肌肉和皮肤的自我修复能力，最近开发了许多合成的自修复超分子聚合物。这些聚合物惊人的自修复特性源自可逆键（“r-键”），它们将聚合物链交联成动态网络。这些r键可以在断裂或解离后自主重组，这可以通过动态共价键、氢键、金属配体配位、疏水相互作用和离子相互作用来实现。由于这些r键，超分子聚合物可以在分子或微观尺度上修复断裂或损伤，并在宏观尺度上恢复其机械强度。这些聚合物已应用于广泛的工程应用，包括柔性电子、储能设备、生物材料、软机器人和晶格结构。考虑到它们的多功能性，研究断裂超分子聚合物所需的愈合时间和恢复的界面强度至关重要。然而，由于实验中使用的r键和聚合物链不同，报道的特征愈合时间涵盖了从几秒到几天的广泛值。例如，Sitti 和同事通过用串联重复肽对生物合成蛋白质进行编程来设计自愈材料。这些合成蛋白质可以形成具有通过β-折叠动态交联的柔性链的超分子网络。通过在断裂附近局部加热至43°C以上，其多肽材料可以在一秒内自愈，机械强度为2−23 MPa。 Leibler 和同事使用脂肪二聚酸通过小分子之间的氢键构建超分子材料网络。其材料的界面强度在 6 小时愈合后可恢复至 2.5 MPa 收稿日期：2021 年 2 月 11 日 修订日期：2021 年 5 月 5 日 发布日期：2021 年 5 月 20 日 文章 pubs.acs.org/Macromolecules © 2021 作者。美国化学会出版 5053 https://doi.org/10.1021/acs.macromol.1c00335 Macromolecules 2021, 54, 5053−5064 下载于 20 7. 15 1. 52 .1 65 于 9 月 28 日、2 02 日1 点 1 点 9:40:45（世界标准时间）。请参阅：//p ub s。交流 s。或g/分享有关如何合法分享发布文章的选项的行。
Supramolecular polymers are fascinating materials due to their strikingly self-healing capabilities empowered by reversible bonds. However, due to the lack of knowledge about the molecular structure evolution at the fractured interfaces, there is no existing theory to explain and predict the diverse healing times of different supramolecular materials observed in experiments. Here, we systematically study the self-adhesion of both unentangled and entangled supramolecular polymer networks through molecular simulations. We find that the recovery of macroscopic interfacial strength almost linearly depends on the microscopic molecular formations at fractured interfaces of supramolecular polymers, including reversible bonds and entanglements (entangled systems only). More importantly, we place the healing time into the context of intrinsic relaxation timescales of supramolecular polymer networks. It is found that the intrinsic sticky Rouse time features the self-adhesion process of all fractured supramolecular polymers, representing the full recovery of interfacial strength. At this critical timescale, two things happened to guarantee the full recovery of fractured systems: (i) polymer chains have diffused across the fractured interface with a displacement comparable to their sizes; (ii) the crossed stickers and polymer chains have updated their reversible bonds and entanglements (entangled systems only), respectively. The clear molecular description and suggested characteristic self-adhesion time will help the molecular design of supramolecular polymers. ■ INTRODUCTION To mimic the self-repairing capability of human muscles and skins, numerous synthetic self-healable supramolecular polymers have been recently developed. The strikingly selfhealing properties of these polymers arise from reversible bonds (“r-bonds”) that cross-link polymer chains as a dynamic network. These r-bonds can autonomously reform after breaking or dissociation, which can be achieved through dynamic covalent bonds, hydrogen bonds, metal−ligand coordination, hydrophobic interactions, and ionic interactions. As a result of these r-bonds, supramolecular polymers can repair fracture or damage at the molecular or microscopic scale and restore their mechanical strength at the macroscopic scale. These polymers have been applied to a wide range of engineering applications, including flexible electronics, energy storage devices, biomaterials, soft robotics, and lattice structures. Considering their versatility, it is of paramount importance to study their required healing time and recovered interfacial strength for fractured supramolecular polymers. However, due to different r-bonds and polymer chains used in experiments, the reported characteristic healing times cover a wide range of values from a few seconds to a few days. For instance, Sitti and co-workers designed self-healing materials by programming biosynthetic proteins with tandem repeat peptides. These synthetic proteins can form a supramolecular network with flexible chains dynamically cross-linked by β-sheets. Through local heating above 43 °C near the fracture, their polypeptide materials can self-heal in a second with a mechanical strength of 2−23 MPa. Leibler and co-workers used fatty dimer acids to fabricate supramolecular material networking by hydrogen bonds between small molecules. The interfacial strength of their materials can recover to 2.5 MPa after a 6 h healing Received: February 11, 2021 Revised: May 5, 2021 Published: May 20, 2021 Article pubs.acs.org/Macromolecules © 2021 The Authors. Published by American Chemical Society 5053 https://doi.org/10.1021/acs.macromol.1c00335 Macromolecules 2021, 54, 5053−5064 D ow nl oa de d vi a 20 7. 15 1. 52 .1 65 o n Se pt em be r 28 , 2 02 1 at 1 9: 40 :4 5 (U T C ). Se e ht tp s: //p ub s. ac s. or g/ sh ar in gg ui de lin es f or o pt io ns o n ho w to le gi tim at el y sh ar e pu bl is he d ar tic le s.