Sulfonated carbon nanotubes/sulfonated poly(ether sulfone ether ketone ketone) composites for polymer electrolyte membranes

Abstract

A series of composite membranes consisting of sulfonated carbon nanotubes (sCNTs) and sulfonated poly(ether sulfone ether ketone ketone) were successfully fabricated via the solution casting method. The chemical structure, as well as the long‐term stability of the sCNTs in different solvents, was investigated by Fourier transform infrared (FTIR) analysis and solubility experiment, respectively. The morphology, tensile strength, proton conductivity, and methanol permeability of the composite membranes were also investigated. The scanning electron microscope (SEM) observation indicated the good dispersion of the carbon nanotubes in polymer matrix as well as the strong interfacial bonding between the sulfonated poly(ether sulfone ether ketone ketone) (SPESEKK) matrix and sCNTs. The addition of either pristine carbon nanotubes or modified carbon nanotubes significantly enhanced the tensile strength of the SPESEKK membrane. The proton conductivity of the SPESEKK membrane increased while the methanol permeability decreased as the sCNTs content increased, showing a strong interaction between the modified nanotubes and SPESEKK. Copyright © 2010 John Wiley & Sons, Ltd.

Sulfonated fullerene in SPEEK matrix and its impact on the membrane electrolyte properties in direct methanol fuel cells

“…It is observed that tensile strength is not much affected by the addition of 0.25 and 0.5 wt.% Sfu to SPEEK matrix in relation to SPEEK. Interestingly at higher loading of Sfu (1 wt.%) slight increase in tensile strength is observed may be attributed to the interfacial hydrogen bonding between Sfu and the host matrix [44], and the reduction in elongation may be due to the increased rigidity of the membranes in the presence of Sfu additive affecting the chain flexibility of SPEEK. It is important to note from Table 2 that variation in tensile strength for the membranes is not prominent in water sorbed environment.…”

“…Whereas for sulfonated fullerene, symmetric and asymmetric stretching vibrations of O=S=O from sulfonic acid (-SO 3 H) group are observed between 1090 and 1392 cm -1 respectively. The bands at 1630 cm -1 is due to C=C stretching and 1740 cm -1 are attributed to the presence of carbonyl group of -COOH [43] and in the lower region, C-S stretching band is observed at 710 cm -1 [44].…”

“…For the temperatures 30 °C and 60 °C, lower methanol permeability of composite membranes than pristine SPEEK is due to the presence of sulfonated fullerene which offers tortuous path for methanol diffusion through the membrane [44]. It is also important to note that methanol permeability of SPEEK based membranes is less in comparison to Nafion-117.…”

“…The addition of Sfu improves the connectivity between the proton conducting channels of sPEEK through hydrogen bonding (represented in Scheme 2) providing the facile transport of protons through the membrane [44]. However at higher loading of the additive (beyond 0.5 wt.…”

The Separation Power of Nanotubes in Membranes: A Review

“…Although most applications of carbon nanotubes in fuel cells are related to their use as electrodes and catalyst support (which is outside the scope of this review), they also play a role in improving the membrane structure. Zhou et al [184] developed composite membranes consisting of sulfonated carbon nanotubes (sCNTs) and sulfonated poly(ether sulfone ether ketone ketone) for use in fuel cells. They found that the addition of either PETA PEO Ketoprofen pristine carbon nanotubes or modified carbon nanotubes significantly enhances the tensile strength of the membrane; the proton conductivity increased while the methanol permeability decreased as the sCNTs content increased.…”