Structure of the ion-rich phase in DVB cross-linked graft-copolymer proton-exchange membranes
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Structure of the ion-rich phase in DVB cross-linked graft-copolymer proton-exchange membranes. / Balog, Sandor; Gasser, Urs; Mortensen, Kell; Ben youcef, Hicham; Gubler, Lorenz; Scherer, Günther G.
In: Polymer, Vol. 53, No. 1, 2012, p. 175-182.Research output: Contribution to journal › Journal article › Research › peer-review
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TY - JOUR
T1 - Structure of the ion-rich phase in DVB cross-linked graft-copolymer proton-exchange membranes
AU - Balog, Sandor
AU - Gasser, Urs
AU - Mortensen, Kell
AU - Ben youcef, Hicham
AU - Gubler, Lorenz
AU - Scherer, Günther G.
PY - 2012
Y1 - 2012
N2 - We report on correlations between the proton conductivity, the water swelling and the dry-state morphology of ETFE-g-poly(sulfonated styrene-co-DVB) proton-exchange membranes (PEMs). We focus on the influence of the systematically varied monomer composition. Especially, the impact of the DVB cross-linker on the ion-rich phase aggregated in the dry PEM is studied by small-angle X-ray scattering. A modified hard-sphere fluid model describing the ion-rich phase is applied to interpret the observed scattering function. We find hereby that the size and number density of the ion-rich domains decrease with increasing cross-link level. Consequently, the distance between the ion-rich domains is proportional to the cross-link level. The total volume fraction of water in the hydrated membrane is proportional to the overall volume fraction of the ion-rich phase, and the number of water molecules per ion-rich aggregate is inversely proportional to the level of cross-linking. We show that there is a clear correlation between the structure of the ion-rich phase formed in the dry state and the proton conductivity of the hydrated membrane: beyond a threshold, indicating the onset of percolation of the aqueous network, the conductivity is proportional to the hydration level and inversely proportional to the mean distance between the ion-rich domains.
AB - We report on correlations between the proton conductivity, the water swelling and the dry-state morphology of ETFE-g-poly(sulfonated styrene-co-DVB) proton-exchange membranes (PEMs). We focus on the influence of the systematically varied monomer composition. Especially, the impact of the DVB cross-linker on the ion-rich phase aggregated in the dry PEM is studied by small-angle X-ray scattering. A modified hard-sphere fluid model describing the ion-rich phase is applied to interpret the observed scattering function. We find hereby that the size and number density of the ion-rich domains decrease with increasing cross-link level. Consequently, the distance between the ion-rich domains is proportional to the cross-link level. The total volume fraction of water in the hydrated membrane is proportional to the overall volume fraction of the ion-rich phase, and the number of water molecules per ion-rich aggregate is inversely proportional to the level of cross-linking. We show that there is a clear correlation between the structure of the ion-rich phase formed in the dry state and the proton conductivity of the hydrated membrane: beyond a threshold, indicating the onset of percolation of the aqueous network, the conductivity is proportional to the hydration level and inversely proportional to the mean distance between the ion-rich domains.
KW - Graft-copolymer
KW - Proton-exchange membrane
KW - SAXS
U2 - 10.1016/j.polymer.2011.11.023
DO - 10.1016/j.polymer.2011.11.023
M3 - Journal article
VL - 53
SP - 175
EP - 182
JO - Polymer Communications (Guildford, England)
JF - Polymer Communications (Guildford, England)
SN - 0032-3861
IS - 1
ER -
ID: 37592684