length Multiple regression analysis of the chemical components effect on wettability at ps laser micro-structured surfaces on stainless steel 304

Recently, controlling the wettability of metallic surfaces by laser micro-structuring has become important for many technical applications. However, understanding the chemical effects on the contact angle (CA) remains a challenge, as there is still a large gap in knowledge about the influence of laser micro-structuring on surface chemistry. In this study, the relationship between the CA and the local surface chemistry and topography at ps laser micro-structured surfaces on stainless steel 304 was discussed by using a new model description. This new model proposed for the first time to express the value from the polar part and dispersive part of the surface free energy (SFE) in terms of the linear combination of each chemical concentration and to obtain their coefficients by multiple regression analysis. The proposed model was verified using experimentally determined data of the wetting behavior of different liquids on surfaces with different surface chemistry characterized by X-ray photoelectron spectroscopy (XPS). The proposed model showed a good correlation between the predicted and the measured CA. As a result, the model can account for the effects of multiple chemical concentrations and predict not only the CA for water but also the CA for different liquids.