Search

In this laboratory experiment, students modify a series of surfaces and explore the effects of varying surface chemistry and texture on wettability by different probe liquids. Students begin by building a simple contact angle goniometer utilizing their mobile phone cameras. Next, they contrast the wettability of planar glass substrates functionalized with alkyl silanes and fluorinated alkyl silanes and calculate surface free energies using Owens/Wendt plots. Subsequently, they synthesize ZnO tetrapods as robust textural elements and spray deposit the tetrapods onto stainless steel meshes to develop hierarchical texturation, which upon subsequent surface functionalization yields superhydrophobic and oleophobic surfaces. The series of experiments allow them to investigate the manner in which textured surfaces deviate from Young's equation and provide a vivid illustration of the thermodynamics of surface wettability. The laboratory exercise further provides a striking visual analogy for illustrating free energy landscapes and serves as a tangible means to demonstrate the role of surface chemistry with regards to the midstream oil-transportation infrastructure.