Preparation of superhydrophobic and self-cleaning polysulfone non-wovens by electrospinning: influence of process parameters on morphology and hydrophobicity

Abstract

Electrospinning is used to prepare hydrophobic and self-cleaning polysulfone (PSf) surfaces. The effects of PSf concentration in Dimethylformamide (DMF) solvent and electrospinning process parameters on the surface structure and hydrophobicity are investigated. The experimental results show that depending on PSf concentration, three types of morphologies are obtained: beads, beads-on-strings, and free-beads fibers. The surface hydrophobicity depends mainly on the resultant surface morphology, and the existence of beads increases hydrophobicity. The contact angle (CA) is found to increase from 73°for smooth PSf surface to more than 160°for surfaces formed by electrospinning. Moreover, the contact angle hysteresis (CAH) was generally less than 10°f or all the chemistries. It is noted that increasing the PSf concentration leads to the formation of beads-on-string and freebeads fiber structures; this morphological change is accompanied by a reduction in the contact angle. Surface structures are found to be more sensitive to electrospinning feed rate than to electrospinning voltage; however, these two parameters have a negligible influence on the hydrophobicity. Porosity measurements of different chemistries show an average pore size in the range 3-8 microns. The thickness of PSf mats was variable, from as low as 10 μm to as high as 70 μm.

Optimizing the electrospinning conditions of polysulfone membranes for water microfiltration applications

“…This indicates that the voltages as assigned in this study, i.e. 12.5, 15 and 18 kV, are within a proper range for the formation of uniform bead‐free PSU fibers, although the region of the applied voltage differs from previous research on the electrospinning of PSU in DMF solution …”

“…This at a constant voltage decreases the coulombic repulsion forces that oppose the stretching of the polymeric solution resulting in the formation of fibers with larger diameter. The ascending trend in the fiber diameter with feed rate has been observed for the electrospinning of other polymers …”

“…with minimum fiber diameter, was obtained for 25% (wt/vol) PSU in DMF at a voltage of 20 kV, 1.5 mL h −1 feed rate and 15 cm distance between the nozzle and the collector. Al‐Qadhi et al . studied the effect of solution concentration, voltage and feed rate on the morphology and the surface hydrophobicity of electrospun PSU ( M w = 35 000 g mol −1 ) mats.…”

“…considering the effect of only one factor at a time, and therefore optimized conditions cannot be deduced (Table ). Typically, Al‐Qadhi et al . studied three parameters and each at a least four levels but performed the electrospinning only for 25 runs, whereas a thorough evaluation requires 144 runs.…”

Fabrication of PEOT/PBT Nanofibers by Atmospheric Pressure Plasma Jet Treatment of Electrospinning Solutions for Tissue Engineering

“…On a rough surface, such as a nanofibrous mesh containing multiple beads, air was trapped in the apertures which could increase the hydrophobicity as the WCA of air is considered to be around 180°. On the contrary, when the surface is bead‐free, the WCA would decrease and would continue to decrease with increasing fiber diameters as higher diameters mean larger contact areas between the water droplets and the polymer surface, and hence lower WCA values . The values reported in Table were thus the result of two factors: surface chemistry and surface morphology (Table S1, Supporting Information, shows the results of WCA for spin‐coated films for the same experimental conditions).…”