Crosslinker mobility weakens transient polymer networks
Crosslinker mobility weakens transient polymer networks
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DOI：
10.1103/physreve.98.062503
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发表时间：
2018-12-26
影响因子：
2.4
通讯作者：
Koenderink, Gijsje H.
中科院分区：
文献类型：
--
作者：
Mulla, Yuval;Koenderink, Gijsje H.
由短寿命键连接的聚合物组成的瞬态网络是生物和合成材料的常见设计主题。瞬态键可以提供机械刚性，同时在超过键寿命的时间尺度上仍然允许粘弹性流动。在许多生物聚合物网络中，如肌动蛋白细胞骨架，短寿命的键是由分离后扩散的辅助蛋白形成的。相比之下，合成网络中的键，如远旋聚合物的垂坠基团，只能在同一位置重新结合。使用最近开发的粘弹性材料断裂理论模型，我们在这里研究了在应力作用下连接剂迁移率对网络键动力学的影响。我们发现，虽然平均场性质（如平均键连接剂寿命）几乎不受键迁移的影响，但由移动键交联的网络更容易破裂，因为连接剂从裂缝区域“泄漏”到网络内应力较小的区域。我们提出了一个理论模型来描述移动链接器的再分配，并通过仿真验证了该模型。我们的工作为细胞面临的潜在权衡提供了见解，即断裂强度与移动连接器提供的模块化和紧密动态控制之间的权衡。
Transient networks composed of polymers connected by short-lived bonds are a common design theme for biological and synthetic materials. Transient bonds can provide mechanical rigidity, while still allowing for viscoelastic flows on timescales longer than the bond lifetime. In many biological polymer networks, such as the actin cytoskeleton, the short-lived bonds are formed by accessory proteins that diffuse away after unbinding. By contrast, bonds in synthetic networks, such as the pendant groups of telechelic polymers, can only rebind in the same location. Using a recently developed theoretical model of the fracturing of viscoelastic materials, we here investigate the effect of linker mobility on the bond dynamics of a network under stress. We find that although mean-field properties such as the average bond linker lifetime are barely affected by bond mobility, networks crosslinked by mobile bonds fracture more readily due to "leaking" of linkers from crack areas to less-stressed regions within the network. We propose a theoretical model to describe the redistribution of mobile linkers, which we validate by simulations. Our work offers insight into a potential tradeoff that cells face, between fracture strength versus the modularity and tight dynamic control offered by mobile linkers.