Adhesion Anisotropy between Contacting Electrospun Fibers

The mechanical properties of electrospun fiber networks are critical in a range of applications from filtration to tissue engineering and are dependent on the adhesion between contacting fibers within the network. This adhesion is complex as electrospun networks exhibit a variety of contacts, including both cross-cylinder and parallel fiber configurations. In situ atomic force microscopy (AFM) was used to quantify the work of adhesion between a pair of individual electrospun polyamide fibers using controlled orientations and measurable contact areas. The work of adhesion was found to depend strongly on the fiber–fiber contact, with the separation of fibers in a parallel fiber configuration exhibiting considerably higher work of adhesion across a range of contact lengths than a cross-cylinder configuration. Our work therefore highlights direction-dependent adhesion behavior between electrospun fibers due to a suggested polymer chain orientation mechanism which increases net van der Waals interactions and indicates the variability of adhesion within a random electrospun fiber network.