In material science, particularly focused on the design and formation of new separation materials, the assessment of wettability is an essential point. Based on the contact angle value, it is possible to select the best membrane materials for the process to ensure the highest effectiveness and performance. There are many requirements to the membrane samples depending on the process, e.g. stability, pore size, porosity as well as roughness and hydrophobic or hydrophilic character. To evaluate the latter ones, the goniometry method must be applied. Based on the mentioned approach, it is possible to determine not only the character by simple water contact angle measurement of the material but to calculate a variety of factors describing the physiochemistry of the membranes, e.g. surface free energy with its components, critical surface tension, and to plot so-called Kao and Zisman diagrams. Based on these parameters, it is possible to predict the interactions between the membrane material and separated system, to prepare suitable washing mixtures for membranes that will prevent wetting and subsequently maintain the membrane stability, to study membrane stability by detecting liquid tension of the feed solution and made the goniometric measurements under similar conditions with the experimental ones. Moreover, by the implementation of fringe projection phase shifting method, it is possible to measure the contact angle corrected by roughness. It should be stressed that roughness has a very important influence on the contact angle, where increasing amounts of roughness tend to boost up the existing properties of the material. To understand in the most precise way how the modification of membrane materials will influence materials features and, as a consequence, the transport and separation, it is must know the contact angle as well as roughness.
In work, a broad range of applications of the goniometry technique in membrane science will be presented.