Determination Of Surface Energy Of Hydrophobic Interfaces Through Contact Angle Measurements

Hydrophobic interactions have been under investigation for decades and questions regarding how forces in these interactions behave continue unanswered. We believe these interactions cannot be explained through existing force laws. We did surface force measurements using the Surface Force Apparatus (SFA) and developed a force law to explain the nature of hydrophobic interactions. We need to determine the surface energy term, a parameter in the proposed hydrophobic force law. We intend to determine its value by measuring contact angles between the hydrocarbon/polymer-air-water interface, then ultimately calculate the surface energy by using Young-Laplace Equation. We plan to accomplish this by utilizing mica templated gold on flat glass surfaces and covalently attaching thiol Self Assembled Monolayers (SAMs). Next, we will videotape the experiment as the contact angle forms between the hydrocarbon/polymer-air-water interface while injecting different pH and salt solution concentrations over the thiol-gold surface. We expect different results in contact angle values based on solution conditions. This will help us determine the interfacial energy of the interface, which will be used in fitting data obtained from SFA measurements. After analyzing our experimental results, we will have supporting data for the SFA force vs. distance measurements for hydrophobic interfaces. Research we are conducting on hydrophobic forces will allow for greater understanding of this fundamental hydrophobic force law and will be applicable to all hydrophobic interfaces that exist around us. This will revolutionize understanding of interactions involved in biological systems.