移动接触线介观过渡区流动的实验研究

The wetting and spreading of the fluid on solid substrate are ubiquitous in nature and human daily life, in which moving contact line remains a fundamental physical problem. The study of the fluid flow in the mesoscopic region near the contact line, on one hand connects the macroscopic capillary flow and the microscopic interface molecular effects, and on the other hand can reply to the still debated flow mechanism and its influencing factor. Thus is a key issue to understand the physical mechanism of the moving contact line. In this study, we will utilize the TIRF experimental system based on evanescent wave, to directly measure the velocity distribution of the mesoscopic flow by NanoPTV method. We will also develop a novel method to measure the dynamic moving contact line profile h(x,y) based on the same system. Furthermore, a simultaneous measurement of both the velocity distribution and the dynamic moving contact line profile will be performed using high viscous fluids. The mesoscopic measured velocity could be used to establish a bridge to couple the macro-scale capillary flow based on hydrodynamic theory and the micro-scale molecular motion, in order to demonstrate the typical flow status in different regions and study the effects influencing flow field in mesoscopic region. The simultaneous measurement of both the velocity distribution and the dynamic moving contact line profile could provide direct connection between the hydrodynamic model and the dynamic contact angle model, and study the interaction between the velocity field and the moving contact line profile. This project can help further investigate the mechanism of the moving contact line, and contribute to the understanding of multiple physical effects near the moving contact line in depth.

液体在固体表面浸润与铺展是自然界及人类生活中常见的现象，移动接触线是其中的基本物理问题。接触线附近介观过渡区流动的研究，既可同时关联宏观毛细区及微观分子区的流动速度，又可解释目前研究中尚存疑问的动态接触线附近流动物理机制及其影响因素，因而具有重要研究意义。本申请拟采用隐失波TIRF实验系统，通过NanoPTV方法直接测量介观过渡区内的速度分布，并采用隐失波分子荧光法(MF)测量动态接触线剖面形貌函数h(x,y)，进而实现速度场及接触线形貌的在位同步测量。速度测量结果可直接耦合宏观毛细区及微观分子区的速度，给出接触线附近各区的特征流态，研究介观区速度场的影响因素；而对介观区速度场及形貌h(x,y)的同步测量，可为水动力学模型及动态接触角模型的耦合提供依据，研究速度与接触线形貌的相互影响及耦合关键参数。本申请将有助于深入考察移动接触线相关的物理机制，全面理解接触线附近区域的多种物理作用。

液体在固体表面浸润与铺展是自然界及人类生活中常见的现象，移动接触线(MCL)是其中的基本物理问题。接触线附近介观过渡区流动的研究，既可同时关联宏观毛细区及微观分子区的流动速度，又可解释目前研究中尚存疑问的动态接触线附近流动物理机制及其影响因素，因而具有重要研究意义。本研究主要在以下四个方面开展了工作：(1)发展了针对动态接触线附近区域测量的隐失波TIRF新实验方法；(2)将介观过渡区内的速度分布测量与动态接触线剖面形貌函数h(x,y)测量结合，测量了接触线附近各区的特征流动，研究介观区速度场的影响因素；(3)研究了动态接触线附近扎钉机制并给出了受力模型；(4)研究了通过咖啡环效应利用移动接触线实现不同组分纳米颗粒自组装的新方法，扩展了本工作的应用前景。相关研究成果也被初步应用于解决微纳尺度界面泳动的实验测量中。本基金工作很好地完成了研究计划，在国内外著名学术期刊上发表了大量研究成果，其结果有助于深入考察移动接触线相关的物理机制，全面理解接触线附近区域的多种物理作用。