Nanocomposite Anion Exchange Membranes with a Conductive Semi-Interpenetrating Silica Network

Abstract

Nanocomposite anion exchange membranes were synthesized based on poly(sulfone trimethylammonium) chloride. A hybrid semi-interpenetrating silica network containing a large amount of quaternary ammonium groups was prepared by two sol–gel routes, in situ with a single precursor, N-trimethoxysilylpropyl-N,N,N-trimethylammonium chloride (TMSP), or ex situ mixing two precursors, TMSP and 3-(2-aminoethylamino)propyldimethoxy-methylsilane (AEAPS). The properties of these hybrid composites and their degradation after immersion in 1 M KOH at 60 °C were studied. The degradation is reduced in the composite materials with a lower decrease in the ion exchange capacity. FTIR spectra showed that a main degradation mechanism with a single precursor TMSP is the dissolution of the hybrid silica network in KOH, whereas it is stable with the mixture of TMSP/AEASP. This conclusion is in agreement with the thermogravimetric analysis. The mechanical properties show a better ductility with a single precursor and higher stiffness and strength, but less ductility, by the ex situ route. The activation energy was between 0.25 and 0.14 eV for Cl and OH ion conduction, respectively, consistent with the migration mechanism.

A novel anion exchange membrane based on silicone/polyphenylene oxide with excellent ionic conductivity for AEMFC

“…The WU rate of QPPO‐Si‐5 membrane (55.6 ± 3.3) was lower than that of QPPO membrane (95 ± 5.3) at 80°C. This is due to the added inorganic filler formed a SiOSi three‐dimensional network cross‐linked structure inside the anion‐exchange membrane, which improved the dimensional stability of the QPPO‐Si‐x membrane 14,27 …”

“…The cross‐linked structure can be used to introduce inorganic components, and the three‐dimensional network cross‐linked structure formed by it can greatly contribute to the mechanical strength of the anion exchange membrane with high ion exchange capacity (IEC) 11,12 . However, the presence of cross‐linked structures in the polymer molecular structure may hinder the anion transport and reduce the electrical conductivity of the membrane 13,14 . Therefore, the problem between the method of cross‐linking and conductivity of the membrane should be concerned.…”

Silica Containing Composite Anion Exchange Membranes by Sol–Gel Synthesis: A Short Review

“…Recently Sgreccia et al prepared membranes based on TMA-quaternized PSU containing a semi-interpenetrating silica network formed by 3-(trimethoxysilyl) propyl-N,N,N-trimethylammonium chloride (TMSP) or by TMSP and 3-(2-aminoethylamino)propyldimethoxy-methylsilane (AEAPS) [ 90 ]. The composite with only TMSP showed better properties in term of ductility and conductivity due to a better homogeneity, although the composite with TMSP and AEAPS presented a more stable network in alkaline conditions ( Figure 7 ).…”

Mechanically robust hydrophobized double network hydrogels and their fundamental salt transport properties

“…Such mechanical support structures increase the composite membrane thickness, thereby reducing flux and limiting efficiency. In response to this challenge, freestanding semi‐IPNs have been prepared using a highly charged first network, often with an arylene backbone, and a rigid, second network, usually crosslinked or coordinated to the first 5–7,28–34 . While these materials have provided relatively low water content (<50 wt%) and high ion exchange capacity (IEC >1 mmol/g), they often exhibit low strains at break, and high Young's moduli.…”

“…In response to this challenge, freestanding semi-IPNs have been prepared using a highly charged first network, often with an arylene backbone, and a rigid, second network, usually crosslinked or coordinated to the first. [5][6][7][28][29][30][31][32][33][34] While these materials have provided relatively low water content (<50 wt%) and high ion exchange capacity (IEC >1 mmol/g), they often exhibit low strains at break, and high Young's moduli. Alternatively, DNHs with reduced water content (~44 wt% water 35,36 ) have been reported, yet they lack strongly disassociating fixed charge groups, while DNHs with the requisite ion exchange groups have only been reported down to ~75-80 wt% water.…”