Electrospray Polytetrafluoroethylene Membranes: Effect of Composition and Heat Treatment on Mechanical Properties and Chemical Resistance

Electrospray is a promising method for fabricating semipermeable polytetrafluoroethylene (PTFE) membranes. PTFE membranes are attractive for filtration and separation in harsh environments, but their mechanical properties depend strongly on crystallinity and thermal history. In this work, PTFE/poly(ethylene oxide) (PEO) membranes were fabricated by electrospraying aqueous solutions with PTFE/PEO ratios of 98.8/1.2, 97.5/2.5, 95/5, and 90/10 wt.%. Increasing the PEO content increased the solution viscosity from 43–78 to 124 mPa·s and caused a transition from sphere-based to mixed fiber–sphere morphology. After sintering at 330 °C, PEO was completely removed and the membrane architecture was preserved. Annealing (slow cooling) produced a more developed folded surface, higher crystallinity, and greater shrinkage, whereas quenching (rapid cooling) retained a less ordered structure, lower shrinkage, and generally higher tensile strength and relative elongation. The highest tensile strength (4.12 ± 0.25 MPa) was obtained for the quenched 97.5/2.5 wt.% membrane, and the highest relative elongation (259 ± 16%) for the quenched 90/10 wt.% membrane. Exposure to nitric acid, potassium hydroxide, dimethyl sulfoxide, motor oil, and distilled water at 100 °C for 48 h caused no statistically significant changes in tensile strength or relative elongation. These results demonstrate that electrosprayed PTFE membranes offer tunable morphology and mechanical properties together with high chemical resistance, making them promising for aggressive-media filtration and separation.