Novel anion-exchange organic–inorganic hybrid membranes prepared through sol–gel reaction of multi-alkoxy precursors

A series of anion-exchange organic–inorganic hybrid membranes were prepared through sol–gel process from different precursors such as the copolymer of glycidylmethacrylate (GMA) and γ-methacryloxypropy trimethoxy silane (γ-MPS) (multi-silicon), N-triethoxysilylpropyl-N,N,N-trimethylammonium iodine (A-1100(+), mono-silicon) and monophenyltriethoxysilane (EPh) (mono-silicon). Influence of the copolymer's molecular weight on the sol–gel process and membrane formation is primarily investigated. It is demonstrated that copolymer with lower molecular weight (number average molecular weight, Mn, 8248) is more desirable to obtain homogenous and flexible hybrid membranes. Results also show that increasing the content of A-1100(+) could increase the membrane water uptake (WR), ion exchange capacity (IEC) and membrane potential (Em), while decrease in EPh content can result in an increase in WR, Em, and elongation at break (Eb). Generally speaking, the membranes have relatively strong hydrophobicity and high mechanical strength. The tensile strength (TS) can reach up to 88 MPa, and the Eb is in the range of 34–41%. Morphology studies show all the hybrid membranes are compact and homogenous even though they have high silica content (27.0–29.8%).