Design And Synthetic Method Of Novel Triazole Proton Exchange Membrane

Proton exchange membrane fuel cell (PEMFC) has been drawing more attention in recent years due to its high efficiency and environmental benignity. PEM plays an important role in conducting proton, segmentating fuel and oxidizer and catalyst support. One of the commercial membranes is perflurinated sulfonic membrane (Nafion) which is applied in PEMFCs due to its high proton conductivity. But its practical application is limited because of its low working temperature (about 80℃) and higher relative humidity (RH). N-heterocyclic compounds with conjugate ring and protogenic proton in structure can be applied in fuel cells. As the International Collaboration Project (Design and Synthesis of Novel N-heterocyclic PEM, No:104300510009), a novel PEM was designed and synthesized based on 1H-1,2,3-triazole functional group in this paper.Firstly, the thermodynamic analysis was done according to the heat and Gibbs function change of 4-methoxybenzyl alcohol(A) chlorination and 1-(chloromethyl)-4-methoxybenzene azide substitution estimated by means of Benson's and Joback's Group Contribution Method. The results showed that the two reactions are feasible.Secondly, using 4-methoxybenzyl alcohol as raw material,1-(4-methoxybenzyl)-4-((3-(trimethoxysilyl)propoxy)methyl)-1H-1,2,3-triazole (Ⅳ) was synthesized through A chlorination (Ⅰobtained, 1-(chloromethyl)-4-methoxybenzene, yield 90.1%), azide substitution (Ⅱobtained,1-(azidomethyl)-4-methoxybenzene, yield 93%), cycloaddition (Ⅲobtained,1-(4-methoxybenzyl)-4-hydroxymethyl-1,2,3-triazole, yield 86.7%) and condensation reaction (Ⅳobtained). The structures ofⅠ,Ⅱ,ⅢandⅣwere characterized by FTIR and NMR and the thermal stability ofⅢandⅣwere determinated by DSC. The optimum conditions were obtained through orthogonal test design and single factor experiments: n(Ⅲ):n((3-chloropropy)trimethoxysilane):n(KOH)=1:1.18:1.14,64℃,52h. The yield ofⅣwas 90.61%.Thirdly, micromonomer 4-((3-(trimethoxysilyl)propoxy)methyl)-1H-1,2,3-triazole(Ⅴ) was obtained by removing the protection group fromⅣ. The optimum conditions were obtained through orthogonal and single factorial test design:52h,70℃and the yield ofⅤis 76.50%. The structure ofⅤwas characterized by FTIR, NMR, DSC and molecular weight and degree of polymerization ofⅤwere tested by GPC. Results showed that the thermal stability ofⅤis good (decomposed at 200℃). Molecular weight distribution is narrower, and its molecular weight 491 and polymerization degree 1.9.Finaly, PEM bearing 1,2,3-triazole functional group was synthesized by in-situ poly-merization.. Its performance and was tested DSC and SEM. Results showed thatⅤbears good thermal stability(decomposed at 570℃) and compact morphology.