Department of Material Science and Chemical Engineering, Stony Brook University, Stony Brook, NY 11794, USA.
Soft Matter. 2017 Mar 1;13(9):1853-1861. doi: 10.1039/c6sm02543a.
We use molecular dynamics simulations to study structure formation in physically associating nanocomposite hydrogels. Nanofillers were modeled as rigid bodies of disk-like shapes and physical crosslinks were simulated by introducing a short-range attraction between the nanofillers and polymer chain ends. The structure, dynamics and mechanics of these polymer gels were studied as a function of nanofiller volume fraction. We observe the formation of a percolated network in the hydrogels, with an ordered local structure but disordered globally, as we increase the filler fraction. This locally ordered structure was a result of the anisotropy of the disk-like fillers. The dynamics of polymers showed significant caging effects in the gel state. Stress autocorrelation and elongation results were analyzed as a function of nano-filler concentrations. Comparisons with nanofillers of different shapes showed that disk-like nanofillers are more effective in strengthening the hydrogels than spherical nanofillers.
我们使用分子动力学模拟来研究物理缔合纳米复合水凝胶中的结构形成。纳米填料被建模为圆盘状的刚体，并且通过在纳米填料和聚合物链末端之间引入短程吸引力来模拟物理交联。我们研究了这些聚合物凝胶的结构、动力学和力学性质作为纳米填料体积分数的函数。随着填充剂分数的增加，我们观察到水凝胶中形成了一个渗透网络，具有有序的局部结构但整体无序。这种局部有序结构是圆盘状填料各向异性的结果。聚合物的动力学在凝胶状态下表现出明显的笼效应。分析了应力自相关和伸长率结果作为纳米填充剂浓度的函数。与不同形状的纳米填料的比较表明，圆盘状纳米填料比球形纳米填料更有效地增强水凝胶。
