Superhydrophobic and Oleophobic Fibers by Coaxial Electrospinning

Abstract

Control of surface wetting properties to produce strongly hydrophobic or hydrophilic effects is at the heart of many macro- and microfluidic applications. In this work, we have investigated coaxial electrospinning to produce core-sheath-structured nano/microfibers that combine different properties from individual core and sheath materials. Teflon AF is an amorphous fluoropolymer that is widely utilized as a hydrophobic material. Hydrophobic fluoropolymers are normally not electrospinnable because their low dielectric constant prevents sufficient charging for a solution to be electrospun. The first Teflon electrospun fibers are reported using coaxial electrospinning with Teflon AF sheath and poly(epsilon-caprolactone) (PCL) core materials. Using these core/sheath fibers, superhydrophobic and oleophobic membranes have been successfully produced. These coaxial fibers also preserve the core material properties as demonstrated with mechanical tensile tests. The fact that a normally nonelectrospinnable material such as Teflon AF has been successfully electrospun when combined with an electrospinnable core material indicates the potential of coaxial electrospinning to provide a new degree of freedom in terms of material combinations for many applications.

Nanofibers Fabricated Using Triaxial Electrospinning as Zero Order Drug Delivery Systems

“…46 Solvents, solutions of small molecules, or unspinnable diluted polymer solutions can be used as outer fluids to yield a series of modified triaxial electrospun products, similar to those which have been generated using modified coaxial electrospinning. [47][48][49] (4) Implementation of other types of multiple-fluid electrospinning for creating complicated functional nanostructures. Many other types of complicated nanostructures, such as side-by-side or combinations of side-by-side and core-sheath materials, may also be obtained (Figure 1).…”

Superamphiphobic surfaces

“…A coaxial nozzle consists of a central tube surrounded by a concentric annular tube. As reported by Steckl et al, 58 a fluoropolymer Teflon AF2400 40 solution and a common polymer poly (Ɛ-caprolactone) was used as sheath and core material, respectively. Both solutions were separately fed into the coaxial nozzle from which they were ejected simultaneously.…”

Recent developments in polymeric superoleophobic surfaces

“…4(A)], which showed superhydrophobic and oleophobic properties. 64 Teflon AF is a normally nonelectrospinnable material because of its low dielectric constant. The authors combined Teflon AF with an electrospinnable core material and successfully solved the problem.…”