Gangqiang Tang,Yujun Ji,Chun Zhao,Dong Mei,Xin Zhao,Jie Ru,Lijie Li,Yanjie Wang
Ionic polymer metal composite (IPMC) is a kind of smart material that integrates functions of actuating and sensing. In this paper, we demonstrated a new sensing function of IPMC to detect the concentration of ethanol by investigating the effects of ethanol content on the electrical response of IPMC. Benefiting from the ion migration effect in the Nafion matrix , the voltage of IPMC varies with different ethanol concentrations . It was found that the response process of IPMC to ethanol solution can be divided into a rapid response stage caused by concentration difference and a slow response stage caused by uneven mechanical stress. The voltage change caused by the concentration difference was defined as the response voltage, and the sensitivity of the IPMC sensor to ethanol concentration was 4.39 mV. We have demonstrated the good cyclability and stability of IPMC to ethanol by experiments. Furthermore, the IPMC sensor was applied to respiratory monitoring after drinking. It has been proven that the IPMC sensor can monitor the changes in alcohol concentration after drinking, which is of great significance for the prevention of stroke after drinking.
Porous organic cage, a kind of newly emerging soluble crystalline porous material, is introduced to proton-exchange membrane by in situ crystallization. The crystallized Cage 3 with intrinsic water-meditated three-dimensional interconnected proton pathways working together with Nafion matrix generates a composite membrane with highly improved proton conductivity. Different from inorganic crystalline porous materials, like metal–organic frameworks, the organic porous material shows better compatibility with Nafion matrix due to the absence of inorganic elements. In addition, Cage 3 can absorb water up to 20.1 wt %, which effectively facilitates proton conduction under both high- and low-humidity conditions. Meanwhile, the selectivity of Nafion–Cage 3 composite membrane is also elevated upon the loading of Cage 3. The proton conductivity is evidently enhanced without obvious increased methanol permeability. At 90 °C and 95% RH, the proton conductivity of NC3-5 reaches 0.27 S·cm–1, highly improved compared to 0.08 S·cm–1 of recast Nafion under the same condition. This study offers a new strategy for modifying proton-exchange membrane with crystalline porous materials.
A membrane with a low methanol permeability and high proton conductivity ( σ p ) is essential for the effective operation of a direct methanol-based fuel cell. Herein, a bio-metal organic framework was prepared with natural α-amino acids as ligands and then combined with hydrolyzed polyacrylonitrile (PAN) nanofibers (AA-MOF@PAN). The resulting nanocomposite membranes were subsequently integrated into a Nafion matrix (AA-MOF@PAN/Nafion). The –NH 2 groups on AA-MOF@PAN interact with –SO 3 H groups on Nafion, forming long-range acid-base pairs along the interface between the matrix and nanofibers. This interaction creates abundant proton-conducting sites for proton exchange membrane. Notably, the AA-MOF@PAN-4h/Nafion membrane demonstrated an exceptional proton conductivity (σ p ) of 0.25 S cm −1 and a higher power density of 117.61 mW cm −2 compared to the recast Nafion membrane. This study offers valuable insights into the three-dimensional ordered design of a natural α-amino acids as a proton transfer sites and highlighting their potential applications in proton exchange membranes.
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