Finlayson Chris E, Rosetta Giselle, Baumberg Jeremy J
Department of Physics, Prifysgol Aberystwyth University, Aberystwyth SY23 3BZ, UK.
Cavendish Laboratory, Department of Physics, University of Cambridge, Cambridge CB3 0HE, UK.
Materials (Basel). 2021 Sep 14;14(18):5298. doi: 10.3390/ma14185298.
A study is presented of the oscillatory shear-ordering dynamics of viscoelastic photonic crystal media, using an optical shear cell. The hard-sphere/"sticky"-shell design of these polymeric composite particles produces athermal, quasi-solid rubbery media, with a characteristic viscoelastic ensemble response to applied shear. Monotonic crystallization processes, as directly measured by the photonic stopband transmission, are tracked as a function of strain amplitude, oscillation frequency, and temperature. A complementary generic spatio-temporal model is developed of crystallization due to shear-dependent interlayer viscosity, giving propagating crystalline fronts with increasing applied strain, and a gradual transition from interparticle disorder to order. The introduction of a competing shear-induced flow degradation process, dependent on the global shear rate, gives solutions with both amplitude and frequency dependence. The extracted crystallization timescales show parametric trends which are in good qualitative agreement with experimental observations.
本文利用光学剪切池对粘弹性光子晶体介质的振荡剪切有序动力学进行了研究。这些聚合物复合颗粒的硬球/“粘性”壳设计产生了无热的准固体橡胶状介质，对施加的剪切具有典型的粘弹性整体响应。通过光子禁带传输直接测量的单调结晶过程，被跟踪为应变幅度、振荡频率和温度的函数。建立了一个互补的通用时空模型，用于描述由于剪切依赖的层间粘度导致的结晶过程，该模型给出了随着施加应变增加而传播的结晶前沿，以及从颗粒间无序到有序的逐渐转变。引入一个依赖于全局剪切速率的竞争性剪切诱导流动降解过程，得到了具有幅度和频率依赖性的解。提取的结晶时间尺度显示出参数趋势，与实验观察结果在定性上有很好的一致性。
