Wetting behaviors of fluoroterpolymer fiber films

Abstract

Various aspects of electrospun fibers prepared from terpolymer of tetrafluoroethylene (TFE), hexafluoropropylene (HFP), and vinylidene fluoride (VDF) (THV)/acetone solutions at two applied voltages, THV/acetone solutions having Texas montmorillonite with two ratios, and THV/ethyl acetate solutions using two needle sizes are described. Fibers from THV/acetone and THV/ethyl acetate solutions showed shallow indentations and pores, respectively. The clay, functioning as electrospinning agent, did not influence the fiber morphology, but yielded narrower fiber diameter distribution and the thinnest fibers. Heterogeneous fiber diameter distribution and increase in the fiber diameters were observed by lowering the voltage for fibers of THV/acetone solutions. Fibers from THV/ethyl acetate solutions had the largest diameter and the broadest diameter distribution. Electrospun THV fibers having both hydrophobic characteristics with nearly 140° water contact angles and oleophilic properties with oil contact angles less than 45° might have applications in areas such as water/oil separation.

Theoretical Investigation of Wenzel and Cassie Wetting States on Porous Films and Fiber Meshes

“…The wetting transition between the Wenzel and hydrophobic Cassie states on a hydrophobic (cos θ 1 r < 0) fiber mesh ,,− occurs when eqs and are equal; that is, when ε normalv = 1 − 1 + cos nobreak0em.25em⁡ θ 2 cos nobreak0em.25em⁡ θ 1 r { π 2 false( π − θ 1 r + tan nobreak0em.25em⁡ θ 1 r false) − 2 d a } is satisfied. The contact angle θ at this transition point is .25ex2ex cos nobreak0em.25em⁡ θ = − 1 − π a 4 d ( π − θ 1 r + tan ⁡ θ 1 r ) cos nobreak0em.25em⁡ θ 2 1 − π a 4 d ( π − θ 1 r + tan ⁡ θ 1 r ) <...…”

“…The wetting transition between the Wenzel and hydrophobic Cassie states on a hydrophobic (cos θ 1 r < 0) fiber mesh ,,− occurs when eqs and are equal; that is, when is satisfied. The contact angle θ at this transition point is …”

“…Industrial applications of mats or meshes made of electrospun fibers have also spread to a variety of fields, such as self-cleaning, filtration, distillation, water harvesting, and tissue engineering . Because the performance of these applications strongly depends on the wetting properties of fiber mats/meshes, the phenomena of wetting on fiber mats/meshes have been extensively studied in recent years. − Experiments were conducted to clarify the relationship between the water contact angle on a fiber mat/mesh and its morphology (fiber diameter, porosity, and roughness of the fiber surface).…”

Polyurethane-Based T-ZIF-8 Nanofibers as Photocatalytic Antibacterial Materials

“…Compared with the TPU/T-ZIF-8 fiber membrane, the addition of PEG increases the hydrophilic groups in the fiber membrane and decreases the free energy at the fiber membrane/water droplet interface, resulting in a smaller water contact angle and worse hydrophobicity, which shows that the surface of the fiber membrane is more easily wetted by liquid water. Compared with the TPU-PEG/T-ZIF-8 fiber membrane, the water contact angle of the TPU-PEG/ZnCl 2 /T-ZIF-8 fiber membrane is slightly increased, which is due to the smaller average fiber diameter, higher porosity, and more compact fiber membrane after adding conductive salt, leading to better hydrophobicity. − Therefore, considering the photocatalytic antibacterial properties, moisture permeability, and hydrophobicity of fiber membranes, the TPU-PEG/ZnCl 2 /T-ZIF-8 fiber membrane has potential applications in medical dressings.…”

The Asphaltenes: State-of-the-Art Applications and Future Perspectives in Materials Science

“…166 In 2011, Natarajan et al 167 showed how to prepare solid and hollow asphaltene fibers by the electrospinning method, which has the advantage of generating ultrafine fibers with high surface areas, numerous surface functionalities, and improved mechanical performance. 168,169 The unique molecular structures of asphaltenes permit molecular aggregation that helps with processing asphaltenes by electrospinning that produces fibers with diameters ranging from 2 to 20 μm, offering membrane fabrication deprived of any synthetic, complex processing steps and without any requirement of postsurface modifications. Toluene was used as the solvent, and solution concentrations were varied from 20 to 40 wt %.…”