Under alkaline conditions,the aldehyde group is introduced into dibenzo?18?crown?6 (DB18C6) with the help of chloroform (CHCl₃) to prepare dimethyl dibenzo?18?crown?6 (DDB18C6).Then,using DDB18C6 and soluble deacetylated chitin (CTS) as raw materials,Schiff reaction was used to synthesize a grafted crown ether CTS membrane with an increasing mass fraction of small molecule crown ethers,which was named C _a ?CTS membrane (a=m(DDB18C6)/m(C _a ?CTS membrane）).The C _a ?CTS membrane is ion exchanged in alkali solution.The C _a ?CTS membrane absorbs K⁺ through the oxygen hole structure,and then the C _a ?CTSK membrane is prepared.Eeach stage the sample membrane was subjected to structural characterization and performance testing.The results show that with the increase of the crown ether grafting degree,the thermal stability of CTS can be improved;when a=0.20,the grafting degree of C_0.20?CTSK membrane can reach 43.91%,the water absorption rate can reach 168.6%,the IEC value is 1.38 mmol/g. At a temperature of 70 ℃,the conductivity of C_0.20?CTSK membrane can reach 46.8 mS/cm; the introduction of grafting of crown ether improves the alkali resistance stability of this series of membranes. After the C _a ?CTSK series membranes are soaked in 6 mol/L KOH solution for 480 hours, the conductivity decreases only 4.0%.

In order to achieve high ionic conductivity and good alkaline resistance of Polysulfone?based AEMs, chloromethylated polysulfone was prepared by green method, and crown ether?functionalized polysulfone membranes with different triethylamine and amino crown ether contents were then prepared using amino crown ether as cross?linking agent and metal ions and triethylamine as cationic groups followed by crown ether functional polysulfone membrane with triethylamine and triethylamine as cationic groups(PSF?CE _X ?QA_1?X ).The effect of the addition of polyethylene glycol on the membrane properties was explored by introducing the low molecular weight polyethylene glycol (PEG) into the above polysulfone cross?linking membrane.The results shown that the presence of hydrophilic polyethylene glycol helps to facilitate the formation of ordered ion channels in the membrane.The conductivity and alkali?resistant stability of PSF?CE _X ?QA_1?X ?PEG were improved compared to PSF?CE _X ?QA_1?X membrane.Among them, the electrical conductivity of PSF?CE_0.1?QA_0.9?PEG at 80 ℃ is 56.78 mS/cm,which can retain 85% of the original conductivity after alkaline resistance test.In addition,PSF?CE _X ?QA_1?X ?PEG has good dimensional and thermal stability.

This paper in situ introduced a mixture of phytic acid,methanol,water,chromium nitrate nonahydrate,N,N?dimethylformamide in polyvinyl alcohol casting solution, where phytic acid and chromium nitrate nonahydrate formed a metal organic framework (MOF) with a three?dimensional structure. Glutaraldehyde was the crosslinking agent to crosslink polyvinyl alcohol into a network structure, and a series of anion exchange membranes with a porous MOF were constructed for fuel cells（MOF@PVA）. During the experiment, the structure and properties of the membranes were optimized by adjusting the Cr³⁺ content. Characterization and performance test results show that the obtained composite membranes are flat and uniform in morphology, with a large number of pore structures available for OH^- migration and retention of water molecules. Additionally, membrane conductivity, water content, and mechanical properties increase with the rising Cr³⁺ mass fractions. When m(Cr³⁺)/m(conductive film) is 0.012, the conductivity is the highest, that is 24.9 mS/cm. The membrane conductivity is only reduced by 8% after being immersed in a 3 mol/L NaOH solution at 80 ℃ for 168 hours.