The polymer solution for electrospinning was prepared by dissolving 500 mg of PMMA (25 wt %, Mw = 120 000) in 2 mL of DMF overnight. The resulting viscous solution was mixed with various concentrations of R18/F5-TPB and R18/ClO4 (0.5-30 wt % with respect to the polymer concentration). The final concentration of the polymer in DMF was adjusted to 22 wt %. Electrospinning was performed on a FLUIDNATEK LE-10 electrospinning equipment (Bioinicia). Then, 1.5 mL of the above solution was loaded into a 5 mL syringe with a 18 G needle. A constant flow rate of 1.5 mL/h was maintained throughout with the help of a syringe pump. A voltage of 18 kV was applied to the syringe needle, and an aluminum foil was used as the collector. The distance between the needle tip to the collector was adjusted to 15 cm. The fiber mat obtained after the electrospinning was dried in an oven at 80° C for 2 h. It was further dried under high vacuum overnight.