Self-assembled proton conduction networks consisting of SPEEK, NH2-POSS, and IL with enhanced proton conduction and decreased IL loss

Abstract

To enhance the conductivity of sulfonated polyether ether ketone (SPEEK, SP) membrane and avoid the loss of ionic liquid (IL), using aminopropyloligosisiloxane (NH 2 -POSS) as molecular hybrid filler, a self-assembled medium temperature and non-humidified SP/IL/NH 2 -POSS hybrid membrane was prepared. NH 2 -POSS can be assembled into the hydrophilic domain ion phase of SPEEK. In which, –NH 2 of NH 2 -POSS and –SO 3 H of SPEEK formed acid-base pairs at the interface which were conducive to the construction of proton transport channel. In addition, NH 2 -POSS enriched IL in the hydrophilic domain, which retained IL while synergistically increased the conductivity. The results showed that the IL loss rate of SP/IL/NH 2 -POSS-2 membrane was 46.9 wt%, which was about 55.8% of SP/IL membrane; the conductivity of SP/IL/NH 2 -POSS-2 membrane at 200 °C without humidification was 5.51 mS·cm −1 , which was about 4 times that of SP/IL membrane. • Molecular-level network SP/IL/NH 2 -POSS proton exchange membrane was prepared. • -NH 2 and –SO 3 H constructed ordered proton transport channels via acid-base pairs. • IL is enriched on NH 2 -POSS and SPEEK interface through hydrogen bonding. • Acid-base pairs and IL-rich layer synergistically increase proton conductivity.