Preparation And Study Of Poly(2,6-dimethyl-1,4-phenylene Oxide)-based Anion Exchange Membrane Crosslinked By Siloxane

Anion exchange membrane fuel cell(AEMFC)has attracted extensive research due to its excellent performance,bargain price and low permeability.The low conductivity and poor alkali resistance of anion exchange membranes,which are the kernel of anion exchange membranes,impeded their development.At present,we mainly attemp to utilize tertiary ammonium groups with good chemical stability to improve the conductivity of the membranes or harness inorganic components to form physical coating to reduce the alkali resistance of the membranes,attacked by hydroxides.This study aims to prepare novel siloxane-crosslinked polyphenyl ether anion exchange membranes and characterize their comprehensive properties.The details are as follows:(1)After the bromination of polyphenylene ether(BPPO),the Quaternary reaction with N-MethyldiethanolaMine(MDEA)was carried out,and the crosslinker agent 2-(3,4-Epoxycyclohexyl)ethyltrimethoxysilane(EHTMS)undergoes a ring opening reaction with the introduced hydroyl group tohangalong the side chain of polyphenylene ether.The anion exchange membrane with different molar ratio of EHTMS/MDEA was fabricated by sol-gel process.FTIR results showed that the chemical reaction proceeded on schedule and MDEA and EHTMS were successfully blended into the system.SEM results displayed that the overall structure of the membrane was compact and uniform,and there was no obvious phase separation phenomenon.TG test demonstrated that the membrane maintained good thermal stability at 220?.The mechanical properties test showed that the tensile strength of the film could be enhanced by adding proper amount of crosslinking agent,up to 18.73MPa.The ionic conductivity of AEM-20 membrane decreased with the increase of siloxane content,but the increasing cross-linking structure enhanced the alkali resistance of the membrane.The ionic conductivity of AEM-20 membrane at 80?is17.6 mS/cm.After soaking in alkaline solution at 60?for a period of time,AEM-20membrane sustained its ionic conductivity at 9.8 mS/cm with 30%lose.The appropriate crosslinking agent endow the membrane with superior chemical stability and enhance its entire performance.(2)TMHDA/siloxane crosslinked polyphenylene ether anion exchange membrane was manufactured by sol-gel technique with synergistic effect of TMHDA/EHTMS,a crosslinking agent,was used to prepare.~1H NMR and FTIR proved that the chemical reaction was conducted punctually.SEM and TG results showed that the overall structure of the film was compact and uniform,and its thermal stability was satisfactory at 220?.The mechanical properties test showed that the toughness of the film increased with the increase of TMHDA content,and the tensile strength also escalated,culminating at 19.67 MPa.The results of IEC,water absorption and swelling test displayed that the water absorption of EHTMS membranes with TMHDA as crosslinking agent is higher than that of EHTMS membranes with the same content,which improves the ionic conductivity of the membranes,and the membranes still have good dimensional stability.IEC and ionic conductivity measurements showed that the ionic conductivity of AEM-3 membrane was refined by adding TMHDA.The conductivity of AEM-3 membrane increased from 11.6 mS/cm at 30?to 19.2 mS/cm at 80?when the content of crosslinker was 20%.The alkali resistance test showed that the chemical resistance of extra TMHDA could slightly decline,but hardly impair itsthe performance.TMHDA,a synergistic crosslinking agent of EHTMS,is a boon for improving the overall performance of the membrane.