Experimental investigation of the free surface evolution at the moving contact line of the polymeric fluids

CBET-0730251 Hossein P. Kavehpour，加州大学洛杉矶分校该项目是一项实验研究，旨在探索聚合物流体移动接触线附近自由表面和纳米结构的演变。最近的理论和实验研究表明，高度缠结的聚合物熔体的自由表面的形状可能会显着不同。在润湿流体的移动接触线的前部存在一层微观膜，称为前体层。这种薄膜的结构已经在理论上进行了研究，但以前的实验研究受到捕获此功能的完整范围所需的测量系统（横向或垂直）的分辨率的限制。在高度缠结的聚合物熔体的运动接触线附近的自由表面具有另一种类型的结构，称为“足区”。“由于高剪切应力，这种结构是由于在移动接触线附近形成未缠结的聚合物而产生的。微观前体膜的存在对于这些类型的流体仍然是可能的。我们的初步实验已经显示了这样的结构，但还需要更多的实验。PI将使用相移激光反馈干涉仪（psLFI）和全内反射荧光显微镜（TIR-FM）测量移动接触线附近扩展液滴轮廓的演变。psLFI系统具有约10 nm的垂直分辨率和0.5 μ m的横向分辨率。该系统将在宏观和微观水平上测量自由表面的演化。TIR-FM系统可以检测距离基底约100 nm的荧光物质。该系统通常用于单细胞分子动力学，尚未用于研究接触线现象。TIR-FM的范围和分辨率使其成为此类实验的理想工具。实验结果将与现有的理论预测进行比较。这项研究的智力价值在于这样一个事实，即大多数以前的实验对这个问题没有适当的时间和空间分辨率，以充分量化这一现象。使用psLFI和TIR-FM将提供更好地研究各种复杂流体的移动接触线所需的分辨率和动态范围。这些实验将首次揭示前驱体膜的三维结构。广泛的影响将使许多工业领域受益，从涂料和油漆行业到。此外，这笔赠款将进一步培训一名博士。研究生和本科生研究员，因此将研究和教育结合起来。

CBET-0730251Hossein P. Kavehpour, University of California-Los AngelesThis project is an experimental investigation to probe the evolution of the free surface and nano-structures in the vicinity of the moving contact line for polymeric fluids. Recent theoretical and experimental investigations have shown that the shape of the free surface may be markedly different for highly entangled polymer melts. A microscopic film, which is known as the precursor layer, exists at the front of the moving contact line for wetting fluids. The structure of this thin film has been studied theoretically, but previous experimental investigations were limited by the resolution of the measurement system (lateral or vertical) required to capture the complete scope of this feature. The free surface close to the moving contact line of highly-entangled polymer melts features another type of structure, called the "foot region." This structure arises from formation of unentangled polymers close to the moving contact line, due to the high shear stress. The existence of the microscopic precursor film is still a possibility for these types of fluids. Our preliminary experiments have shown such structures but additional experiments are necessary. The PI will measure the evolution of the profile of a spreading droplet near the moving contact line using a phase-shifted laser feedback interferometer (psLFI) and a total internal reflection fluorescence microscope (TIR-FM). The psLFI system has the vertical resolution of approximately 10nm and lateral resolution of 0.5im. This system will measure the free surface evolution at the macroscopic and microscopic levels. The TIR-FM system can detect fluorescence materials approximately 100nm from the substrate. This system, commonly used on single cell molecule dynamics, has not been used to study the contact line phenomena. The range and resolution of the TIR-FM makes it an ideal tool for such experiments. The experimental finding will be compared with the available theoretical predictions. The intellectual merit of this investigation rests on the fact that most of the previous experiments done on this problem did not have appropriate temporal and spatial resolution to fully quantify this phenomena. Using psLFI and TIR-FM will provide resolution and dynamic range required to better investigate the moving contact line of a variety of complex fluids. These experiments will reveal three dimensional structure of precursor film for the first. The broad impact will benefit numerous industrial fields, from coating and paint industries to. In addition, this grant will further the training of a Ph.D. graduate student and an undergraduate researcher and therefore integrate research and education.