Enhanced anhydrous proton conductivity of SPEEK/IL composite membrane embedded with amino functionalized mesoporous silica

The novel SP/IL/AMS composite membrane doped with amino-functionalized mesoporous silica (AMS) was successfully prepared. Sulfonated poly ether ether ketone (SPEEK, SP) was used as the polymer matrix and the ionic liquid (IL) was N -ethylimidazolium trifluoromethanesulfonate (EIm[Tfo]). Its properties were compared with SP/IL/NMS composite membrane doped with non-functionalized mesoporous silica (NMS). Fourier transform infrared spectroscopy (FT-IR) analysis indicated that the components in the composite membrane were bound by intermolecular forces. In addition, an acid-base interaction was formed between -NH 2 in AMS and -SO 3 H in SPEEK. The acid-base pair is beneficial to proton conduction. The anhydrous proton conductivity of SP/IL/3-AMS-7.5 composite membrane is about 4 times higher than that of the SP/IL/NMS-7.5. In addition, the good interfacial compatibility between AMS and polymer matrix is conducive for creation continuous proton transfer channel. Thermogravimetric analysis (TG) showed that all composite membranes were stable at 270 °C. The leaching of IL data indicated that IL can be effectively retained due to the presence of -OH and -NH 2 on the NMS and AMS surfaces. The SP/IL/AMS composite membrane could be used in proton exchange membrane fuel cells under medium temperature and anhydrous conditions.