Syntheses, Functionalization And Proton Conductivity Over Wide Temperature Range Of Porous Organic Polymers

Proton exchange membrane fuel cells (PEMFCs) are very promising as a replacement for traditional engines due to their high power density and ultralow emission features. The state-of-the-art PEMFCs with Nafion as electrolytes can reach a conductivity on the order of 10-1-10-2 S cm-1 under a limited condition with moderate temperature (60-80 ?) and high relative humidity (98% RH). To date, most studies are intended to imrove temperature range of the PEM, while overlooking the temperature to solve the defect of CO poisoning and lower operating temperature to reduce power consumption to beginning. Our group has conducted a study on the proton conductivity of the imidazole loaded polyimide polymer. The functional proton exchange membrane can promise the proton stable transport over wide range temperature (-40 ?-90 ?), but can not get over the CO poisoning because of the not enough high temperature. Hence, in the thesis, we will obtain proton conductivity over wide temperature range via indroducing high stability porous organic polymer and loading high boiling guest molecules. The tetrahedral tetraphenylmethane was used as the primitive material, and a serial of tetrahedral building blocks, poly-(tetrakis (4-carbazoleyphenyl)-methane (POP-1) and poly-(tetrakis (4-phenyl)-methane) (POP-2), were synthesized. Proton conductors, Im@POP-1? Im@POP-2 and Tr@POP-1, were received by loading guest molecules of imidazole or 1,2,3-triazole into the polymers, POP-1 and POP-2. Im@POP-1 and Im@POP-2 showing the proton conductivities in wide temperature range of high temperature between 30 ? and 200 ?, exhibited proton conductivities of 1.92×10-4 S cm-1 and 7.78×10-4 S cm-1, respectively. And the values of the Ea are 0.19 eV /0.56 eV and 0.34 eV/0.63 eV, respectively, both belonging to Grotthuss mechanism and Velicle mechanism. Compared, the part of the proton conductivity in wide temperature of low temperature,-30 ?-110 ?, Tr@POP-1 presented proton conductivities of 2.7×10-7 S cm-1 at-30 ? and 4.88×10-5 S cm-1 at 110 ?. The value of the Ea of 0.14 eV /0.38 eV also pertained to Grotthuss mechanism, importantly the 0.14 eV being the lowest in the proton conductors. In conclusion, the paper obtained anhydrous proton exchange membrane over wide temperature range by emplying the different porous organic polymer frameworks and guest molecules, extending the proton conductivity temperature range of the porous organic polymers, importantly broadening the practical application forward of proton exchange membrane fuel cells.