Influence of surface topography and chemistry on the wetting behavior of laser-patterned, metallic surfaces

表面的润湿行为对其抗菌剂、摩擦和磨损性能或附着力有重大影响。激光图案化的过程允许系统地改变表面的润湿特性。能量的局部应用改变了表面化学和地形，这两者都对润湿性能有影响。本文系统地研究了金属表面激光图案化对其润湿性能的影响。特别是，相关的关键参数应借助实验和模拟的方法来确定。第一个目标是生成和表征激光图案化铜样品，并创建合适的模拟模型。对于激光图形，使用了非常精确和高效的直接激光干涉图形（DLIP）方法。采用三种不同的脉冲激光系统（ns, ps, fs），利用不同的激光材料相互作用，这取决于脉冲持续时间，以获得不同的表面化学相似的形貌。首先，不均匀表面化学的影响是通过溅射过程来平衡的。生成的样品的形貌和表面化学将使用高分辨率技术进行分析，以便创建合适的模拟模型。使用了三种不同的方法：能量最小化、粗粒度分子动力学（MD）模拟和全原子分子动力学模拟。此外，化学均匀表面的润湿行为是由宏观和特别开发的方法（偏最小二乘算法）确定的，具有高空间分辨率。第二个目标是用上述方法模拟化学均匀样品的润湿行为。主要的激光模式，表面化学和叠加的纳米粗糙度的影响将被研究。在此基础上，对连续介质方法和MD模拟进行了比较，为进一步进行多尺度模拟奠定了基础。最后的目标是确定在激光图案，化学不均匀表面润湿的关键参数，并比较实验和模拟。特别是，将评估模拟方法的可预测性和所需的计算工作量。这是激光图案金属表面润湿行为领域的一个里程碑，因为到目前为止，相关文献还没有达成共识。

The wetting behavior of surfaces has drastic effects on their antimicrobial, friction and wear properties, or their adhesion. The process of laser patterning allows to change the wetting properties of surfaces systematically. The local application of energy modifies both the surface chemistry and the topography, which both have an influence on the wetting properties.The present proposal systematically investigates the influence of laser patterning of metallic surfaces on their wetting properties. In particular, the relevant key parameters shall be identified with the aid of experimental and simulative methods.The first goal is the generation and characterization of laser-patterned copper samples and the creation of suitable simulation models. For laser patterning, the extremely precise and efficient method of Direct Laser Interference Patterning (DLIP) is used. Three different pulsed laser systems (ns, ps, fs) are used in order to obtain different surface chemistry with similar topography by exploiting the varying laser material interaction, which depends on the pulse duration. First, the effect of an inhomogeneous superficial chemistry is to be egalized by sputtering processes. The resulting topography and surface chemistry of the produced samples will be analyzed using high resolution techniques in order to create suitable simulation models. Three different approaches are used: energy minimization, coarse grained molecular dynam-ics (MD) simulations, and fully atomistic MD simulations. Furthermore, the wetting behavior of the chemically homogeneous surfaces is determined both macroscopically and by a specially developed method (Partial Least Squares Algorithm) with high spatial resolution.The second goal is the simulation of the wetting behavior of the chemically homogeneous samples with the above mentioned methods. The influence of the primary laser pattern, the surface chemistry, and a superimposed nano-roughness will be investigated. Furthermore, continuum approach and MD simulations will be compared, which is an important prerequisite for further multi-scale modelling.The final goal is to identify the key parameters in the wetting of laser-patterned, chemically inhomogeneous surfaces and to compare experiment and simulation. In particular, the pre-dictability and the required calculation effort of the simulation methods will be evaluated.This is a milestone in the field of the wetting behavior of laser-patterned metallic surfaces, as there is no consensus in the relevant literature so far.