Karl Christian W, Krauklis Andrey E, Lang Andrej, Giese Ulrich
Materials and Nanotechnology Dept., SINTEF Industry, Forskningsveien 1, 0373 Oslo, Norway.
German Institute of Rubber Technology (DIK e. V.), Eupener Str. 33, 30519 Hanover, Germany.
Polymers (Basel). 2020 Jul 10;12(7):1528. doi: 10.3390/polym12071528.
The wetting of rough polymer surfaces is of great importance for many technical applications. In this paper, we demonstrate the relationship between the mean roughness values and the fractal dimension of rough and self-affine PTFE surfaces. We have used white light interferometry measurements to obtain information about the complex topography of the technical surfaces having different height distributions. Two different methods for the calculation of the fractal dimension were used: The height difference correlation function (HDC) and the cube counting method. It was demonstrated that the mean roughness value () correlates better with the fractal dimension determined by the cube counting method than with the values obtained from HDC calculations. However, the HDC values show a stronger dependency by changing the surface roughness. The advancing and receding contact angles as well as the contact angle hysteresis of PTFE samples of different roughness were studied by the modified Wilhelmy balance technique using deionized water as a liquid. The modified Wilhelmy balance technique enables the possibility for future analysis of very rough PTFE surfaces which are difficult to investigate with the sessile drop method.
粗糙聚合物表面的润湿性对于许多技术应用而言至关重要。在本文中，我们阐述了粗糙且具有自仿射性的聚四氟乙烯（PTFE）表面的平均粗糙度值与分形维数之间的关系。我们利用白光干涉测量法获取了有关具有不同高度分布的工业表面复杂形貌的信息。使用了两种不同的分形维数计算方法：高差相关函数（HDC）和计盒法。结果表明，平均粗糙度值与通过计盒法确定的分形维数的相关性优于与从HDC计算获得的值的相关性。然而，HDC值随表面粗糙度的变化显示出更强的依赖性。采用改进的Wilhelmy天平技术，以去离子水为液体，研究了不同粗糙度的PTFE样品的前进接触角、后退接触角以及接触角滞后现象。改进的Wilhelmy天平技术为未来分析难以用静滴法研究的非常粗糙的PTFE表面提供了可能。
