He HongRui, Lee Jonghun, Jiang Zhang, He Qiming, Dinic Jelena, Chen Wei, Narayanan Suresh, Lin Xiao-Min
Materials Science Division and Center for Molecular Engineering, Argonne National Laboratory, Argonne, Illinois 60439, United States.
Pritzker School of Molecular Engineering, University of Chicago, Chicago, Illinois 60637, United States.
J Phys Chem B. 2023 Aug 24;127(33):7408-7415. doi: 10.1021/acs.jpcb.3c03290. Epub 2023 Aug 10.
The macroscopic rheological response of a colloidal solution is highly correlated with the local microscopic structure, as revealed by an Rheo-SAXS experiment with a high temporal resolution. Oscillatory shear can induce a strain-controlled ordering-to-disorder transition, resulting in a shear-thickening process that is different from the normal shear-thickening behavior that is driven by hydrodynamics and particle friction. We reveal that there is a complex time-dependent kinetics toward structural ordering under different applied strains. When the strain amplitude reaches a critical value that starts to induce disordering in the system, the pathway toward the dynamic equilibrium can also become highly non-monotonic. Within the same oscillatory cycle, there is a strong correlation of ordering with different phases of the oscillation, with the system oscillating between two dynamic metastable states.
如具有高时间分辨率的流变小角X射线散射实验所揭示的那样，胶体溶液的宏观流变响应与局部微观结构高度相关。振荡剪切可引发应变控制的有序到无序转变，从而导致一种剪切增稠过程，该过程不同于由流体动力学和颗粒摩擦驱动的正常剪切增稠行为。我们揭示，在不同的外加应变下，存在着朝向结构有序化的复杂的时间依赖性动力学。当应变幅度达到开始在系统中引发无序化的临界值时，朝向动态平衡的路径也可能变得高度非单调。在同一个振荡周期内，有序化与振荡的不同相位之间存在很强的相关性，系统在两个动态亚稳态之间振荡。
