粒子悬浮中的剪切厚度与动态刷层的粒子悬浮
Hojin Kim1,2, Michael van der Naald1,3, Finn A Braaten1,3
1James Franck Institute, The University of Chicago, Chicago, Illinois 60637, USA. hojinkim718@gmail.com.
Soft matter
|July 31, 2024
概括
研究人员探索了分子桥梁,以控制悬浮中的粒子摩擦和质学. 这种方法诱导了剪切加厚,改变了粒子相互作用,提供了调整流体行为的新方法.
科学领域:
- 软物质物理学 软物质物理学
- 结合体科学 结合体科学
- 类风病学 类风病学 类风病学
背景情况:
- 控制液体悬浮颗粒中的摩擦相互作用是可调节,非牛顿式风学的关键.
- 传统的方法依赖于物理接触,粒子形状和表面粗度来控制摩擦.
- 使用分子桥梁的新方法为控制粒子相互作用提供了一个新的机制.
研究的目的:
- 研究分子桥梁作为一种方法,以产生对相对粒子运动的可控约束.
- 了解表面功能化体颗粒和远程分子聚合物之间的动态共价键如何影响质性质.
- 描述剪切加厚的开始及其对粒子大小的依赖.
主要方法:
- 使用了表面功能化的体颗粒,能够与远程分子聚合物形成动态共价键.
- 在不同剪切应力下研究了质反应,重点关注过渡到剪切加厚.
- 使用功率定律分析分析了开始剪切应力 (σ*) 与粒子直径的依赖性.
- 测量了第一个正常应力差异 (N1) 和外推的体积分数,以在剪切加厚模式下阻塞.
主要成果:
- 在低切割应力下,粒子形成一个均的聚合物刷层.
- 在开始应力 (σ*) 以后,发生分子桥接,导致剪切加厚.
- 开始应力 (σ*) 显示出对粒子直径的电力定律依赖,其指数为-1.76.
- 剪切厚度的加大伴随着N1的扩张和阻塞体积分数的减少,这表明与粒子大小的减少一起有效粒子摩擦的增加.
结论:
- 分子桥梁提供了一种可控制的途径,以诱导体悬浮液中的剪切加厚.
- 观察到的现象,包括 σ* 的粒子大小依赖性和增强的摩擦,与悬浮物的理论预测一致.
- 这项研究提供了通过受控的粒子间相互作用来设计具有可调节的质性质的先进材料的见解.
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