The Influences Of The Self-crosslinking Hybridization And The Post Functionalization To The Structure And The Performance Of Anion Exchange Membranes

Two series of alkaline anion exchange membranes were prepared. The first is a group of cross-linked multiblock copoly(arylene ether sulfone) ionomer/nano-Zr O2(CLQCPAES/nano-Zr O2) composite anion exchange membranes, and the second is a family of partially fluorinated poly(arylene ether) containing side-chain aromatic benzyltrimethyl ammonium groups. The characterizations of the membranes include structure characterizations, water uptake, swelling ratio, hydroxyl ion conductivity, thermal properties, mechanical properties, and alkali stability test.The series of cross-linked multiblock copoly(arylene ether sulfone) ionomer/nano-Zr O2(CLQCPAES/nano-Zr O2) composite anion exchange membranes were prepared via block copolymerization, bromomethylation, ultrasonication blending, self-crosslinking, quaternization and alkalization. The structure and surface and cross section morphology of the CLQCPAES/nano-Zr O2 composite membranes were characterized by solubility test, FT-IR, XRD and SEM analyses. The combination of the determining results reveals that the CLQCPAES/nano-Zr O2 composite membranes are complex cross-linking networks of hydrophobic domains/hydrophilic domains/nano-Zr O2 with clear zonal distribution of uniform nano-sized particles in the hydrophilic domains when the nano-filler loading below 7.5%. Basic performances of the CLQCPAES/nano-Zr O2 composite membranes are assessed to investigate their application in fuel cells in terms of water uptake, swelling ratio, ion exchange capacity(IEC), hydroxide conductivity, thermal and mechanical properties, and alkaline stability. The modification of anion exchange membranes with multiblock ionomer structure, cross-linking technique and the introduction of nano-Zr O2 particles greatly enhance the water uptake, hydroxide conductivity, mechanical properties and alkaline stability of the composite membranes. Particularly, the CLQCPAES/7.5%Zr O2 membrane with an IEC value of 1.23 mmol g-1 exhibits the best comprehensive properties and constitutes a good potential candidate of anion exchange membrane used in AEMFCs.By designing partially fluorinated main chain structure and introducing functional side-chain aromatic benzyltrimethyl ammonium groups, we synthesized and prepared another family of alkaline anion exchange membrane with different IEC values. Solubility test shows that the prepared membranes can’t dissolve in chloroform, as well as in high boiling point polar aprotic solvents when IEC values are high. Infrared spectrum analysis shows that the membranes have successfully quaternized. Small Angle X-ray diffraction analysis indicates the existence of nano phase separation in the membranes structures. Partially fluorinated main chain structure and the functional side chain groups greatly improved the performance of the membranes, such as water uptake, swelling ratio and conductivity. The QFPAE-95 membrane has the highest hydroxyl ion conductivity, which reaches to 108.6 m S cm-1 at 80 oC. The QFPAE-55 membrane has the maximum tensile strength of 21.01 MPa. Ea value of the QFPAEs membranes increases with the increasing of the IEC value. The QFPAE-55 membrane remains 82.3% and 84.2% of its conductivity and IEC value respectively after soaked in 1 M Na OH solution at 60 oC for 20 days.