D. Yang, H. Baker, O. Keyes
Ebatco,
United States
Keywords: surface free energy, micro contact angle, nano, measurement scale influence
Summary:
Surface free energy is the excessive energy existing on the surface of a solid due to imbalanced intermolecular forces among molecules of a solid. Surface free energy provides a more general characterization of a surface, chemically and thermodynamically, and its analysis is of significance to numerous applications such as wetting, cleaning, contamination, adhesion, friction, lubrication, and wear. By using different probe liquids with known polar, non-polar, and hydrogen-bond energy components, the surface free energy of a solid surface can be determined through contact angle measurements. In addition to surface free energy analysis, contact angle measurements have been used in studies for the purposes of better understanding and control of wettability, hydrophobicity, hydrophilicity, and biocompatibility of materials. It is known that contact angles determined on the surfaces can be influenced by surface chemistry as well as surface topographical features, such as nano and microscale patterns, and surface roughness. In this study, contact angle measurements and surface free energy analysis at both micro and macro scales were conducted on glass, PTFE, and polycarbonate surfaces. Contact angle data and surface free energy values obtained at both micro and macro scales were analyzed along with the surface patterns and surface roughness values determined by white light interferometry on the specimen surfaces. Influences from the measurement scale on surface free energy analysis were examined and discussed.