Many surface modification and coating technologies that are used for optimizing wetting and adhesion properties influence both surface chemistry and roughness. Understanding the mechanisms that impact wetting by separating these two factors can be a useful tool in product development processes and in quality control. Roughness correction on contact angles also enables the calculation of fundamental surface free energy on rough surfaces. Theta Topography can be used for studying microscale roughness, which is relevant in many applications and processes. Examples include:
Wettability is typically studied by a contact angle measurement that can be defined with the well-known Young equation on ideal surfaces. Surface free energy theories are also based on assumptions that Young contact angles are used for calculations. Thus, the surface is assumed to be chemically homogenous and topographically smooth. This is, however, not true in the case of real surfaces. It is well established that surface roughness enhances the existing wetting behavior and influence on adhesion. See more details in theory note 7.
Theta Topography makes it possible to define Young contact angle and surface free energy measurements as well as measurements for rough surfaces according to the well-known Wenzel theory. The roughness corrected contact angles make it possible to understand the influence of roughness and chemistry on the wettability of your surface, separately. By using the highly accurate motorized XYZ sample stage, we can perform both measurements from the exact same location and map the complete surface to check homogeneity and cleanliness. With the Theta Topography you can get:
– Θc, roughness corrected contact angles
– 3D and 2D topographical parameters and visualization
The optical image (left), 2D representation (middle), and 3D representation (right) of a paper sample measured with the Attension® Topography.