Semi-Interpenetrating Polymer Network Membranes from SPEEK and BPPO for High Concentration DMFC

Abstract

In the present work, semi-interpenetrating polymer networks (semi-IPNs) fabricated by the in situ synthesis of crosslinking networks between diamine cross-linkers and bromomethylated poly(phenylene oxide) (BPPO) are used toward sulfonated poly(ether ether ketone) (SPEEK) membrane applications for high concentration direct methanol fuel cells (DMFCs). Four kinds of diamine cross-linkers with different structures of hydrophobic flexible, hydrophilic flexible, hydrophobic rigid/ bulky, and hydrophilic rigid/bulky are applied to construct the semi-IPNs. The influences of cross-linkers on the key properties, such as phase separation, water uptake, proton conductivity, and methanol permeability, as well as cell performances, are systematically investigated. The results indicate that fabricating semi-IPNs is an attentive approach to improve the properties of SPEEK. The hydrophobic rigid/bulky fluorine cross-linker is the most effective to reduce methanol permeability, giving rise to the highest power output of the high concentration DMFC. In particular, by analyzing the correlation of cell performances, proton conductivity, and methanol permeability, we note that methanol permeability is more important than proton conductivity for high concentration DMFCs.

Simultaneous improvement of power density and durability of sulfonated poly(ether ether ketone) membrane by embedding CeO 2 ‐ATiO 2 : A comprehensive study in low humidity proton exchange membrane fuel cells

“…The 1 H NMR graph displayed in Figure S5 illustrates the aromatic hydrogen peaks of SPEEK from H 1 to H 14 . The DS of SPEEK was determined to be 66.6% based on the equation below 33 …”

“…The post‐sulfonation process of PEEK was done by following the method described by Liu et al 33 Approximately, 20 g of dried PEEK pellets were gradually added to 200 mL of H 2 SO 4 then the mixture was vigorously agitated using a mechanical stirrer (500 rpm) at 40°C until complete dissolution of PEEK. Afterward, the temperature of the solution was increased to 60°C for 2 hours.…”

“…The DS of SPEEK was determined to be 66.6% based on the equation below. 33 DS ¼ 12 A H1,2,3,4 þ A H6,7,8,9,10,11,12,13,14…”

Simple and Effective Cross-Linking Technology for the Preparation of Cross-Linked Membranes Composed of Highly Sulfonated Poly(ether ether ketone) and Poly(arylene ether sulfone) for Fuel Cell Applications

“…The polymer miscibility is one of the critical issues for the preparation of blend membranes composed of more than two polymers because the phase-separated domains caused by the immiscibility of polymers can produce a physically unstable state and brittleness problems. 31,32 Figure 5 shows the surface and cross-sectional SEM images as well as photo images of CM-Xs. The transparent photo images of CM-Xs indicate that SPEEK88 and SPAES90 are miscible in the range of visible light wavelength size because they have the same sulfonated groups and a similar aromatic structure although they are cross-linked.…”

Development of proton-exchange polymer nanocomposite membranes for fuel cell applications

“…The SPEEK itself or making composite with various additives are reported and utilized as an effective membrane in FC applications. 4 -8 Incorporation of finely dispersed nanoparticles modifies the single-phase pure polymer structure. In general, the proton conductivity can be alleviated by the introduction of inorganic oxides into the pristine membrane.…”