Roughness and Fiber Fraction Dominated Wetting of Electrospun Fiber-Based Porous Meshes

Wettability of electrospun fibers is one of the key parameters in the biomedical and filtration industry. Within this comprehensive study of contact angles on three-dimensional (3D) meshes made of electrospun fibers and films, from seven types of polymers, we clearly indicated the importance of roughness analysis. Surface chemistry was analyzed with X-ray photoelectron microscopy (XPS) and it showed no significant difference between fibers and films, confirming that the hydrophobic properties of the surfaces can be enhanced by just roughness without any chemical treatment. The surface geometry was determining factor in wetting contact angle analysis on electrospun meshes. We noted that it was very important how the geometry of electrospun surfaces was validated. The commonly used fiber diameter was not necessarily a convincing parameter unless it was correlated with the surface roughness or fraction of fibers or pores. Importantly, this study provides the guidelines to verify the surface free energy decrease with the fiber fraction for the meshes, to validate the changes in wetting contact angles. Eventually, the analysis suggested that meshes could maintain the entrapped air between fibers, decreasing surface free energies for polymers, which increased the contact angle for liquids with surface tension above the critical Wenzel level to maintain the Cassie-Baxter regime for hydrophobic surfaces.

电纺纤维的润湿性是生物医学和过滤行业的关键参数之一。在对由七种聚合物制成的由电纺纤维和薄膜制成的三维（3D）网格上的接触角的全面研究中，我们清楚地表明了粗糙度分析的重要性。用X射线光电子显微镜（XPS）分析了表面化学，结果表明纤维和薄膜之间没有显着差异，这证实了仅通过粗糙度就可以提高表面的疏水性，而无需任何化学处理。表面几何形状是电纺网润湿接触角分析的决定因素。我们注意到，如何验证电纺表面的几何形状非常重要。常用的纤维直径不一定是令人信服的参数，除非它与表面粗糙度或纤维或孔隙的比例相关。重要的是，这项研究提供了指南，以验证表面自由能随网眼纤维分数的降低而降低，以验证润湿接触角的变化。最终，该分析表明，网孔可以保持纤维之间的残留空气，从而降低聚合物的表面自由能，从而增加表面张力高于临界Wenzel水平的液体的接触角，从而使疏水表面保持Cassie-Baxter态。

Published: 2019

Journal ：POLYMERS

Impact Factor：3.619

Paper link: https://www.mdpi.com/2073-4360/11/1/34