A multiscale polymerization framework towards network structure and fracture of double-network hydrogels
A multiscale polymerization framework towards network structure and fracture of double-network hydrogels
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DOI：
10.1038/s41524-021-00509-5
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发表时间：
2021-03
影响因子：
9.7
通讯作者：
Mingzhen Zhang;Dong Zhang;Hong Chen;Yanxian Zhang;Yonglan Liu;Baiping Ren;Jie Zheng
中科院分区：
文献类型：
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作者：
Mingzhen Zhang;Dong Zhang;Hong Chen;Yanxian Zhang;Yonglan Liu;Baiping Ren;Jie Zheng
双网络（DN）水凝胶，由两个对比和互穿的聚合物网络组成，被认为可能是最坚韧的软湿材料。目前对DN凝胶从合成方法到增韧机理的认识几乎完全来自于实验上的化学连接DN水凝胶。水凝胶中不均匀DN结构的分子建模和模拟已被证明是极具挑战性的。在此，我们开发了一个新的多尺度模拟平台，以计算研究物理化学连接的琼脂/聚丙烯酰胺（琼脂/PAM）DN水凝胶在长时间尺度的早期断裂。一个“随机游走反应聚合”（RWRP）被开发来模拟自由基聚合过程，这使得能够从单体构建物理化学连接的琼脂/PAM DN水凝胶，同时进行常规和转向MD模拟来检查在松弛和变形状态下的结构依赖性能量耗散和断裂行为。集体模拟结果表明，琼脂/PAM水凝胶的能量耗散归因于从DN中拉出琼脂链，DN结构之间和内部的大量氢键的破坏，以及水分子与两个网络的强关联的组合，从而解释了琼脂/PAM水凝胶的不同机械增强。该计算工作提供了混合DN水凝胶的网络结构、动力学、溶剂化和相互作用的原子细节，以及混合DN水凝胶的不同结构依赖的能量耗散模式和断裂行为，这有助于设计具有新网络结构和有效能量耗散模式的坚韧水凝胶。此外，RWRP算法通常可用于构建自由基聚合产生的水凝胶、弹性体和聚合物。
Double-network (DN) hydrogels, consisting of two contrasting and interpenetrating polymer networks, are considered as perhaps the toughest soft-wet materials. Current knowledge of DN gels from synthesis methods to toughening mechanisms almost exclusively comes from chemically-linked DN hydrogels by experiments. Molecular modeling and simulations of inhomogeneous DN structure in hydrogels have proved to be extremely challenging. Herein, we developed a new multiscale simulation platform to computationally investigate the early fracture of physically-chemically linked agar/polyacrylamide (agar/PAM) DN hydrogels at a long timescale. A “random walk reactive polymerization” (RWRP) was developed to mimic a radical polymerization process, which enables to construct a physically-chemically linked agar/PAM DN hydrogel from monomers, while conventional and steered MD simulations were conducted to examine the structural-dependent energy dissipation and fracture behaviors at the relax and deformation states. Collective simulation results revealed that energy dissipation of agar/PAM hydrogels was attributed to a combination of the pulling out of agar chains from the DNs, the disruption of massive hydrogen bonds between and within DN structures, and the strong association of water molecules with both networks, thus explaining a different mechanical enhancement of agar/PAM hydrogels. This computational work provided atomic details of network structure, dynamics, solvation, and interactions of a hybrid DN hydrogel, and a different structural-dependent energy dissipation mode and fracture behavior of a hybrid DN hydrogel, which help to design tough hydrogels with new network structures and efficient energy dissipation modes. Additionally, the RWRP algorithm can be generally applied to construct the radical polymerization-produced hydrogels, elastomers, and polymers.