Cole Hunzeker is in his final year of undergraduate education at Coe College. He comes from Illinois, USA. Cole’s research has been focused on the preparation and modification of hydrophobic glasses
M. Rusch, C. Hunzeker, Lila Dabill, M. Affatigato Center for the Study of Glass and Physics Department, Coe College, Cedar Rapids, IA
This work was supported by Coe College and by the United States National Science Foundation under grant numbers DMR-1407404, and DMR-1746230.
Our project is modeled based on the lotus leaf. One main function of the lotus leaf’s hydrophobicity is the ability to self-clean: raindrops falling onto the leaf do not disperse but stay in their shape while running over the surface and picking up dirt and dust particles. This ability stems from a two-fold surface engineering: The leaf surface is covered with an intrinsically hydrophobic material, and the surface contains a microscopic pattern that helps water drops keep up their surface tension.
In our project, we made use of both of these effects. In one part of the project we conducted a survey study creating various glasses and testing them for their hydrophobicity. We have come to a conclusion that glasses containing heavy metal oxides are more hydrophobic than glasses without them. We report on the results of the changes in the cleaning process and the surface roughness of the most hydrophobic samples. In the other part of the project we created microscopic patterns on our glasses—using lithographic techniques—to enhance their inherent hydrophobicity. Because creating such patterns on novel glasses is uncommon and therefore challenging, several steps from resist spinning to preliminary lithography and chlorine etching guided us to the desired product. We used borosilicate wafers made of Borofloat 33 glass to test and perfect the etching technique. Then we used the same technique on lead borate wafers (60 mol% PbO, 40 mol% B2O3) that were manufactured by us. The photomask that we used has 16 different patterns that are available during processing. We focused on the same four patterns every time we went through the process for comparison purposes. With the patterns that are used, we have attempted different times for etching to vary the depth of the patterns. Using the fully etched glass, we report on the hydrophobicity of the etched patterns compared to that of the measurements of the unmodified glass.