Time-resolved microstructural changes in large amplitude oscillatory shear of model single and double component soft gels
Time-resolved microstructural changes in large amplitude oscillatory shear of model single and double component soft gels
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DOI：
10.1122/8.0000486
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发表时间：
2022-04
影响因子：
3.3
通讯作者：
G. Donley;Minaspi Bantawa;E. Gado
中科院分区：
文献类型：
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作者：
G. Donley;Minaspi Bantawa;E. Gado
当施加足够的变形时，软颗粒凝胶可以可逆地屈服，并且可以通过设计混合水凝胶复合材料来增强或限制这种转变的特性。虽然这些体系的微观动力学和宏观流变学已经分别进行了详细的研究，但在两者之间建立直接联系一直很困难，特别是在非线性流变学方面。为了弥补这一差距，我们使用粗粒度分子动力学模拟对不同体积分数的模型软颗粒凝胶进行了一系列的振幅振荡剪切（LAOS）数值测量。我们首先研究了具有局部弯曲刚度的颗粒网络，然后将其与可以提供额外交联的第二个组件结合起来，以获得双组件网络。通过物理过程序列（SPP）框架，我们定义了时间分辨的动态模量，并通过跟踪这些模量随时间的变化，我们可以区分材料行为随时间的变化。这种方法通过将动态模量的变化与变形过程中相应的微观结构变化（包括颗粒的非仿射位移、键的断裂、形成和取向）联系起来，帮助我们建立非线性流变的微观起源。
Soft particulate gels can reversibly yield when sufficient deformation is applied, and the characteristics of this transition can be enhanced or limited by designing hybrid hydrogel composites. While the microscopic dynamics and macroscopic rheology of these systems have been studied separately in detail, the development of direct connections between the two has been difficult, particularly with regard to the nonlinear rheology. To bridge this gap, we perform a series of large amplitude oscillatory shear (LAOS) numerical measurements on model soft particulate gels at different volume fractions using coarse-grained molecular dynamics simulations. We first study a particulate network with local bending stiffness and then we combine it with a second component that can provide additional cross-linking to obtain two-component networks. Through the sequence of physical processes (SPP) framework, we define time-resolved dynamic moduli, and by tracking the changes in these moduli through the period, we can distinguish transitions in the material behavior as a function of time. This approach helps us establish the microscopic origin of the nonlinear rheology by connecting the changes in dynamic moduli to the corresponding microstructural changes during the deformation including the nonaffine displacement of particles, and the breakage, formation, and orientation of bonds.