Characterization of water adhesion on electrospun PCL fibres

The study of water wettability is crucial in agriculture, heat exchange, and biomedical applications; however, water adhesion receives limited attention despite being distinct from wettability and lateral pinning forces. Water adhesion is particularly relevant in designing hydrophobic surfaces with high normal adhesion, a property commonly correlated with wettability. Yet, materials with similar wettability can exhibit differences in water adhesion. We examined the water adhesion phenomena on hydrophobic electrospun fibers composed of polycaprolactone (PCL) with varying concentrations of poly(lactide-co-caprolactone) (PLCL) using a micromechanical balance. The aim is to explore how variations in chemical composition and morphology affect water adhesion. Through spreading and withdrawing experiments, as well as comparison with static and dynamic contact angles, we identified a correlation between contact angle hysteresis and the maximum adhesion force. This finding contrasts with previous research that focused solely on receding contact angles, highlighting how contact angle hysteresis provides the best correlation with maximum adhesion force for fibrous hydrophobic surfaces. Given the challenges in measuring contact angle hysteresis on fibrous hydrophobic surfaces, this study also suggests adhesion tensiometry as a potentially more robust and accessible method for these materials.