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Damage and mechanical failure are detrimental for materials in engineering applications. However, recent studies have shown that properly designed debonding and pullout phenomena in composite fractures can be implemented to introduce added functionalities by damage induced surface texturing (DIST). In the DIST approach, randomly oriented or aligned fibers are incorporated in a polymeric matrix, followed by transversal shearing of the surface. As a result, the shear-fractured surface will have protruded fibers on it because of debonding followed by subsequent pullout. The protruded fibers play a key role in imparting new functionalities to the cut surface.
One of the drawbacks of DIST is that the introduced surface functionalities (i.e. hydrophobicity) are affected by mechanical weathering since the commercial carbon fibers used lack abrasion and flexural fatigue resistance. In order to overcome this issue, carbon nanofibers (CNFs) can be used resulting in enhancing the surface wettability of generated surfaces from hydrophobic to the superhydrophobic regime. We have shown that by using 36 wt.% chemical vapor grown hollow carbon nanofibers in styrene-ethylene/butylene-styrene (SEBS) matrices the water sessile-drop contact angle of pristine cut SEBS samples increases by 41% from 106.1˚ ± 2.9˚ to 151.7˚ ± 1.7˚. Although the CNFs are small in diameter size (100 nm) with respect to CFs having two orders of magnitude larger diameters, they provide a high specific surface area of up to ~ 50 m2/g while the latter has a specific area of ~ 1 m2/g. The higher surface area generated by protruded CNFs on the surface can introduce air pockets between the surface and water droplets necessary for surface supperwettability. DIST is a simple, economical, and scalable. In addition, there is no need to use costly and time-consuming post-processing stages to introduce anisotropic properties into the material.
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