A series of novel organic–inorganic hybrid proton exchange membranes (PEMs) were prepared from the sulfonated poly(arylene ether sulfone) with 4-amino phenyl pendant groups (Am-SPAES), (3-isocyanatopropyl) triethoxysilane (ICPTES), and 3-(trihydroxysilyl) propane-1-sulfonic acid with covalent bonds to form network using a sol-gel method. The obtained cross-linked hybrid membranes (Am-SPAES/I-SiO2-S) displayed excellent solvent resistance and thermal and mechanical stability. The Am-SPAES/I-SiO2-S membranes with cross-linking network exhibited a higher proton conductivity (0.043 S cm−1 at 20°C) than PEMs without covalent bonds (Am-SPAES/SiO2-S) and the swelling ratio maintained below 17.00% even at 100°C. Most importantly, all of the obtained membranes showed considerably lower methanol permeability than that of Nafion 117. In addition, the chemical structures and morphologies of the hybrid membranes were characterized by Fourier transform infrared spectroscopy and scanning electron microscopy, respectively.
Developing high-performance protective materials is important for soldiers and civilians who are exposed to the atmosphere of highly toxic chemical warfare agents (CWAs). Polyelectrolyte membranes are promising candidates with excellent chemical resistance and moisture permeability, but they cannot efficiently degrade CWAs. Here, we design and prepare a hybrid membrane through in situ growth of catalytically active zirconium-based metal–organic frameworks (Zr-MOFs) on a polyelectrolyte membrane mediated by biofilm-inspired curli nanofibers (CNFs). Superior to the bare polyelectrolyte membrane, the prepared MOF-808@CNF-PQ hybrid membrane exhibits improved rejection of the nerve agent simulant dimethyl methyl phosphonate (DMMP) vapor and permeation of the water vapor by 113 and 45%, respectively. The water/DMMP selectivity of the hybrid membrane reaches 498.6, approximately 13 times that of the commercial polyelectrolyte membrane Nafion 117. In addition, the hybrid membrane possesses appreciable catalytic activity for the hydrolysis of the nerve agent simulant dimethyl 4-nitrophenyl phosphate (DMNP) with a half-life of ∼38 min. Nanomechanical characterization results based on atomic force microscopy (AFM) techniques demonstrate the critical role of CNFs in mediating Zr-MOF nucleation and the dominant effect of electrostatic interactions on self-assembly of CNFs on polyelectrolyte base. It is also confirmed that the Zr-MOF toppings serve as the key components in physically adsorbing and chemically degrading the DMNP molecules through multiple strong intermolecular interactions. Our work offers a rational strategy to develop advanced membranes toward efficient chemical protection, moisture permeation, and catalytic detoxification against CWAs.
A series of sulfonated polysulfone (SPSU) membranes with different degrees of sulfonation were prepared for fabricating cost-effective and high-performance ionic polymer–metal composite (IPMC) actuators. The experimental results show that the ion exchange capacity and water uptake of SPSU membranes increase with increasing their degree of sulfonation, and the proton conductivities of these hydrated membranes are subsequently enhanced. Compared with the commercial Nafion 117 ion exchange membrane, these SPSU membranes have higher ion exchange capacity and water uptake ability. Furthermore, the higher molecular rigidity of the SPSU membranes leads to higher tensile moduli in both dry and wet states than the Nafion membrane. The IPMC actuators made of the SPSU membranes demonstrate the large bending strain, fast response and excellent fatigue resistance under electric stimulation. Their electromechanical behaviors can be controlled by adjusting the sulfonation level of the SPSU ion exchange membranes.
Hai Qiang Li,Xue Jiao Liu,Jingmei Xu,Da Xu,Hongzhe Ni,Shuang Wang,Zhe Wang
A series of triazole-grafted sulfonated poly(arylene ether ketone sulfone)s (SPTs) were fabricated via an amide coupling reaction between 3-amino-1,2,4-triazole and carboxylic acid group. The degree of sulfonation (DS) was set to 80% for preventing excessive swelling. The chemical structures of synthesized polymers were characterized by Fourier transform infrared spectroscopy (FT-IR) and 1 H NMR spectroscopy . The triazole group affected the properties of membranes dramatically. Increasing the triazole group content was conductive to promoting the thermal property and oxidative stability. And all SPT membranes retained above 92% of their weight after the test in Fenton's reagent at 80 °C for 1 h. The swelling ratio of SPT-3 membrane was only 12.66% and it was lower than that of C-SPAEKS-3 membrane at 100 °C. It was also found that the proton conductivity was distinctly improved by introducing triazole groups and the SPT-4 membrane exhibited a proton conductivity of 0.166 S cm −1 at 120 °C, which was larger than that of Nafion 117. In addition, all SPT membranes showed higher proton conductivity when compared with C-SPAEKS-3 membranes over the range of relative humidity from 20% to 90% at 80 °C.
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