Preparation of the Multicomponent High Temperature Proton Exchange Membranes with Layer by Layer Self-assembly Technique

Layer by layer (LBL) self-assembly technique has been proved to be a feasible method that enables to accomplish the preparation of functional membranes with multilayered structure. In this research, the polymer of sulfonated polyetheretherketone (SPEEK) and thioglycolic acid capping of cadmium telluride (CdTe) nanocrystals as polyanion, the polymer of polyurethane (PU) as polycation have been used to prepare membrane electrolytes. These multilayered membranes showed good thermal stability and exhibited low liquid methanol permeability, which provided a possibility for the prepared membranes as proton exchange membranes (PEMs) to apply in direct methanol fuel cells (DMFCs). We have also demonstrated that the multicomponent (SPEEK/PU/CdTe/PU)₁₀₀ membranes favored to combine more phosphoric acid (PA) molecules and possessed a higher proton conductivity comparing to the bicomponent (SPEEK/PU)₂₁₀ membranes. So PA doped (SPEEK/PU/CdTe/PU)₁₀₀ membrane presented a maximum proton conductivity up to 8.6×10^-2 S/cm at 160 °C under anhydrous conditions. However, PA doped (SPEEK/PU)₂₁₀ membranes underwent a drop on proton conductivity while the temperature exceeded 120 °C.