Application Of Sulfonated Poly(aryl Ether Ketone Sulfone)Polymer Doped With Polyoxometalates Compounds In Proton Conduction Membrane

Sulfonated poly（aryl ether ketone sulfone）is expected to become a substitute for Nafion membranes due to its simple polymerization process,designability of structure,wide operating temperature,and low cost.The performance of sulfonated poly（aryl ether ketone sulfone）membranes is closely related to their degree of sulfonation（DS）.Low DS membranes have good alcohol resistance and anti swelling properties,but their proton conductivity is low;At high DS,although the proton conductivity of the membrane is high,its water absorption,anti swelling performance,and alcohol resistance decrease accordingly.Therefore,the challenge for the further development of PEM lies in selecting the appropriate DS to ensure the high mechanical performance and low methanol permeability of the membrane,while also improving the proton conductivity of the membrane.Polyoxometalates,also known as polyacids（POMs）,are nanoscale metal oxygen cluster compounds formed by the high oxidation states of pre transition metal ions（such as V,Mo,W,etc.）and oxygen.The abundant terminal oxygen and bridging oxygen atoms in POMs serve as hydrogen bonding receptors,which can form a hydrogen bonding network with sulfonic acid groups in the polymer matrix,facilitating proton hopping and improving the proton conductivity of the membrane.Meanwhile,POMs have strong Br（?）nsted acidity and can serve as proton donors,providing additional proton sources and promoting proton conduction.Therefore,combining sulfonated poly（aryl ether ketone sulfone）sulfone with POMs can improve the proton conductivity of sulfonated poly（aryl ether ketone sulfone）sulfone,and prevent POMs from dissolving in water through their electrostatic or hydrogen bonding interactions.The work content of this article is as follows:1.A series of hybrid membranes were synthesized by combining Na₇H₂La W₁₀O₃₆(La W₁₀)with sulfonated poly（aryl ether ketone sulfone）.All hybrid membranes exhibit higher proton conductivity than pure membranes in the temperature range of 30℃ to 80℃.M-La W₁₀-7 exhibits the best proton conductivity at 80℃,up to 64 m S·cm^-1;IEC increased to 0.88 mmol·g^-1;Increase the water absorption rate to 22.5%;E_a decreased to 9.12 k J·mol^-1;The tensile strength reaches 18.37 MPa.The results indicate that the introduction of La W₁₀clusters can serve as proton sources to provide protons,allowing more protons to participate in the conduction process,thereby improving the membrane conductivity and IEC.The abundant terminal oxygen and bridge oxygen in the La W₁₀ cluster can form more hydrogen bonding networks with sulfonic acid groups,reducing the energy barrier of proton hopping and resulting in lower E_a.Meanwhile,due to the hydrophilicity of La W₁₀,the water absorption capacity of the membrane is improved.This work provides a new direction for the modification and application of rare earth elements and POMs containing rare earth elements in proton exchange membranes.2.A series of hybrid membranes were synthesized by combining HMe Im Mo₁₃₂ with sulfonated poly（aryl ether ketone sulfone）.Within the temperature range of 30℃ to 80℃,all hybrid membranes exhibit higher proton conductivity than pure membranes.When the doping amount of HMe Im Mo₁₃₂ reaches 5 wt%,the proton conductivity of the M-5%HMe Im Mo₁₃₂ membrane is the highest.M-5%HMe Im Mo₁₃₂ exhibits the best proton conductivity at 80℃,reaching 75 m S·cm^-1;IEC increased to 0.75 mmol·g^-1;The tensile strength reaches 26.34 MPa;The elongation at break reaches 15.10%;The swelling rate is less than 7%;E_a decreased to 13.05 k J·mol^-1.The large amount of terminal oxygen and nitrogen atoms in methylimidazole in HMe Im Mo₁₃₂ can form a richer hydrogen bond network with the sulfonic acid groups in sulfonated poly（aryl ether ketone sulfone）,with 20irregular hexagonal windows with a diameter of 5（?）in the structure,providing channels for proton conduction pathways and promoting the proton conduction process under the Grotthuss mechanism,resulting in a lower E_a.The introduction of HMe Im Mo₁₃₂ and the addition of hydrogen bonding networks also strengthen the interactions within the polymer,improve the toughness of the membrane,and thus increase the elongation at break of the membrane.Due to the strong acidity of HMe Im Mo₁₃₂,which can dissociate more protons,the IEC of all hybrid membranes is higher than that of pure membranes,further proving that the introduction of HMe Im Mo₁₃₂ can promote proton conduction in the membrane.This work provides a theoretical basis for the modification and application of nitrogen containing POMs in proton exchange membranes.