Membrane casting: To prepare the membranes, homogeneous solutions of STz25 and STz30 in DMF with a solid content of 10% were prepared. These solutions were then poured onto Petri dishes placed on a horizontal glass plate, and the solvent was evaporated at 80 °C with filter paper covering the dishes. After the solvent evaporation, the resulting membranes were carefully delaminated from the glass substrates by immersing in deionized water. The membranes were stored in water until used.