Binary Liquid Mixture Contact-Angle Measurements for Precise Estimation of Surface Free Energy

Area of Science:

• Materials Science
• Surface Chemistry
• Physical Chemistry

Background:

• Surface free energy is a critical parameter for characterizing liquid-solid interfacial interactions.
• Accurate determination of surface energy is essential for predicting material behavior in various applications.
• Existing methods can be limited by solvent purity and measurement precision.

Purpose of the Study:

• To develop a precise and reliable method for determining surface free energy.
• To utilize binary liquid mixtures for enhanced accuracy in surface energy measurements.
• To validate the approach on different hydrophobic surfaces.

Main Methods:

• Contact angle measurements of binary liquid mixtures (water-DMSO, water-formamide, water-ethylene glycol, water-glycerol) on solid surfaces.
• Application of the Owens-Wendt method for surface energy analysis.
• Development of a mixing equation to estimate dispersive and polar surface tension components for binary mixtures.

Main Results:

• The developed method using binary mixtures significantly reduced uncertainty in surface energy determination for polydimethylsiloxane (PDMS) compared to pure solvents.
• Uncertainty decreased to below 13% with three mixtures and around 5% when combining data from four mixtures.
• Consistent surface energy values were obtained for silane-derivatized glass surfaces using different binary mixtures (water-formamide and water-glycerol).

Conclusions:

• Contact angle measurements with binary liquid mixtures offer a simple yet precise method for surface energy determination.
• This approach enhances the accuracy of surface energy measurements, surpassing the precision of using multiple pure solvents alone.
• The findings provide a valuable tool for surface characterization in materials science and related fields.