Effect of water concentration on the shock response of polyethylene glycol diacrylate (PEGDA) hydrogels: A molecular dynamics study
Effect of water concentration on the shock response of polyethylene glycol diacrylate (PEGDA) hydrogels: A molecular dynamics study
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DOI：
10.1016/j.jmbbm.2018.09.017
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发表时间：
2019-02-01
影响因子：
3.9
通讯作者：
Spearot, Douglas E.
中科院分区：
文献类型：
--
作者：
Luo, Ke;Yudewitz, Noah;Spearot, Douglas E.
首次用非平衡分子动力学模拟方法模拟了冲击波在聚乙二醇二丙烯酸酯(PEGDA)水凝胶中的传播。PEGDA水凝胶模型是使用“完美网络”方法构建的，每个交联点由六个链连接组成。在颗粒速度为200-1000m/S的范围内，研究了聚乙二醇二乙二胺浓度(20-70wt%)对冲击行为的影响。与文献报道的类似密度凝胶的实验结果一致，PEGDA水凝胶中的冲击波速度和压力随着聚合物浓度的增加而增加，在纯水和纯聚合物行为的范围内。发现了冲击波压力和冲击波阵面厚度作为浓度的函数的非线性关系，并提出了描述这一行为的对数方程。此外，还用流体力学理论比较了压力与激波阵面厚度的关系。在高颗粒速度下观察到与流体力学预测的偏差，这种偏差被发现与粘度变化有关。在PEGDA水凝胶中，应变速率与压力之间存在着与金属相似的幂定律关系。然而，对于所有凝胶浓度，计算的指数为1.4，而对于金属，通常报告的指数为4。
Shockwave propagation in polyethylene glycol diacrylate (PEGDA) hydrogels is simulated for the first time using nonequilibrium molecular dynamics simulations. PEGDA hydrogel models are built using the "perfect network" approach such that each crosslink junction is comprised of six chain connections. The influence of PEGDA concentration (20-70 wt%) on shock behavior is investigated for a range of particle velocities (200-1000 m/s). In agreement with reported experimental results in the literature on gels with similar densities, shock velocity and pressure in PEGDA hydrogels are found to increase with polymer concentration, within a range bounded by pure water and pure polymer behaviors. Nonlinear relationships are observed for shock pressure and shock front thickness as a function of concentration, and a logarithmic equation is proposed to describe this behavior. In addition, the relationship between pressure and shock front thickness is compared with hydrodynamic theory. Deviation from hydrodynamic predictions is observed at high particle velocities and this deviation is found to be related to viscosity changes. A power-law relationship between strain rate and pressure in PEGDA hydrogels is identified, similar to that of metals. However, a power-law exponent of 1.4 is computed for all gel concentrations, whereas an exponent of 4 is typically reported for metals.