Influence of Mixed Solvent in the Morphology and Hydrophobicity of Electrospun Polystyrene Porous Fibers

Electrospun polystyrene (PS) fibers are produced using a mixed solvent of chloroform and n,n-dimethylformamide (DMF) to investigate the influence of the solvent ratio on the fiber surface morphology and contact angle of the obtained mats. Electrospinning is a simple processing technique for producing fibers with diameters in the range of nanometers to a few micrometers. When using the different solvent ratios for this process, porous PS membranes are created due to nonsolvent and thermally induced phase separation (N-TIPS). The morphology of the fibers is analyzed through scanning electron microscopy (SEM), which showed that fibers have diameters between 200 nm and 6 µm. SEM also revealed that the pores present on the surface of the fibers vary from densely compacted and well-formed nanopores with diameters in the range of 20-50 nm to larger pores with sizes of ≈100-200 nm. The pore size varied with different solvent ratios. The surface area is analyzed using the Brunauer-Emmett-Teller (BET) method and found that the polymeric fibers have a high surface area (≈35 m² g^-1). The fibers with such morphology are highly hydrophobic, with a contact angle higher than 143°. These materials are excellent candidates for applications in textiles, filtration, and biomedical fields.