Colloidal-rods for examining polymer dynamics in complex flows

在2022财政年度，完成了在稳定剪切流下测量不同聚合物溶液中胶体棒排列的实验。测试不同的聚合物解决方案，我们已经能够得出结论，聚合物动力学管理的剪切诱导的胶体棒对齐的发病。具体地，用于棒的对准的控制参数是聚合物溶液的Weissenberg数，量化聚合物对施加的流动的弹性响应。此外，我们发现，胶体棒不认为周围的聚合物溶液作为一个连续的介质，而是像一个离散的介质，胶体棒遵循一个普遍的趋势，是独立于周围的聚合物溶液的对齐。该部分项目已成功完成，并发表于《大分子》2022-55- 13。于2022财政年度，我们亦进行了蠕虫状嵌段共聚物的流动动力学实验。我们表明，剪切和拉伸流诱导蠕虫状嵌段共聚物的排列。然而，我们发现，拉伸变形是更有效的比剪切变形在触发蠕虫状颗粒的对齐的发病。我们解释了剪切变形和拉伸变形之间的对齐的差异的基础上的颗粒的可延伸性和灵活性。该项目的这一部分已成功完成，并发表在《大分子》2022-55-22上。

In FY2022, experiments were completed measuring the alignment of colloidal rods in different polymer solutions under steady shear flows. Testing different polymer solutions, we have been able to conclude that the polymer dynamics govern the onset of shear-induced alignment of colloidal rods. Specifically, the control parameter for the alignment of rods is the Weissenberg number of the polymer solution, quantifying the elastic response of the polymer to an imposed flow. Additionally, we find that the colloidal rods do not perceive the surrounding polymer solution as a continuous medium, but rather like a discrete medium and that the colloidal rods follow a universal trend of alignment that is independent of the surrounding polymer solution. These part of the project has been successfully completed and published in Macromolecules 2022-55-13.In FY2022 we have also conducted experiments on the flow dynamics of worm-like block copolymers. We show that shear and extensional flows induce the alignment of the worm-like block copolymers. However, we find that extensional deformations are more effective than shear deformations at triggering the onset of alignment of the worm-like particles. We explain the difference in alignment between shear and extensional deformations based on the particle extensibility and flexibility. These part of the project has been successfully completed and published in Macromolecules 2022-55-22.