Fabrication and investigation of phosphoric acid doped imidazolium siloxane crosslinked poly(2,6‐dimethyl‐1,4‐phenylene oxide) for high temperature polymer electrolyte membranes

Abstract

A series of high temperature polymer electrolyte membranes were fabricated based on imidazolium poly(2,6-dimethyl-1, 4-phenylene oxide) (PPO) using methylimidazole (MeIm) and triethoxysilylpropyldihydroimidazole (SiIm) as quaternization reagents via the S N 2 nucleophilic substitution. Meanwhile SiIm was also employed as a crosslinking agent and the crosslinked Si-O-Si network was constructed through a hydrolysis procedure of SiIm in an acid medium. Compared with the PPO-100%MeIm membrane without the crosslinking structure, the imidazolium siloxane crosslinked PPO-x%SiIm-y%MeIm membranes exhibited increased acid doping contents, enhanced dimensional stabilities, improved mechanical properties and higher conductivities. The PPO-30%SiIm-70%MeIm/(198 wt% phosphoric acid) membrane displayed a conductivity of 0.08 S cm −1 at 180 ∘ C without humidifying and a tensile strength of 6.4 MPa at room temperature.

Poly(4-vinylpyridine) Based Semi-Interpenetrating Cross-Linked High Temperature Proton Exchange Membranes for Fuel Cells

“…The stress–strain curves were obtained to characterize the mechanical stability of membranes, which were cut to a size of 4 mm in width and 25 mm in length like a dumbbell shape by conducting experiments in an ambient atmosphere using a tensile strength instrument (CMT2000, China) with a crosshead speed of 5 mm min –1 . The in-plane proton conductivity of membranes was measured by AC impedance spectroscopy on a Princeton electrochemical workstation (VersaSTAT 3) with two electrodes based on previous work . The AC frequency ranged from 100 Hz to 100 kHz.…”

“…The in-plane proton conductivity of membranes was measured by AC impedance spectroscopy on a Princeton electrochemical workstation (VersaSTAT 3) with two electrodes based on previous work. 42 The AC frequency ranged from 100 Hz to 100 kHz. All of the conductivity measurements were determined in ambient air, and the temperature was controlled by an oven ranging from 100 to 180 °C without any humidification.…”