Effects of incorporation of fluorocarbon and hydrocarbon surfactants into perfluorosulfonic acid (Nafion) membranes

Journal Article · Fri Jul 01 00:00:00 EDT 1994 · Chemistry of Materials; (United States)

DOI:https://doi.org/10.1021/cm00043a014· OSTI ID:6456783

Rabago, R; Noble, R D; Koval, C A ^[1]

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1. Univ. of Colorado, Boulder, CO (United States)

Perfluorinated ionomer membranes such as Nafion have numerous uses in both industrial chemical practice and in chemical research. Applications include the chloralkali process, H[sub 2]/O[sub 2] fuel cells, biomedical sensing, and other types of chemical sensors based on modified electrodes. Significant permeability improvements can be made to perfluorinated ionomer films by incorporating sulfonated surfactants of suitable size into the membrane microstructure. A variety of 20-[mu]m composite Nafion/surfactant membranes were prepared from DMF casting solutions containing Nafion and the sodium salts of perfluoro-1-butanesulfonic acid (perf-ButSO[sub 3]Na), perfluoro-1-octanesulfonic acid (perf-OctSO[sub 3]Na) and 1-octanesulfonic acid (OctSO[sub 3]Na). The time required for 50% extraction of the surfactants from the membranes into water was 1 min for OctSO[sub 3]Na, 5 min for perf-ButSO[sub 3]Na, and approximately 3 days for perf-OctSO[sub 3]Na. Extraction of perf-OctSO[sub 3]Na into isooctane contacting solutions was not observable over periods of days. For membranes containing surfactants and exchanged with silver(I) ion, 3-fold permeability improvements can be obtained for the separation of 1,5-hexadiene from 1-hexene and n-hexane without any decreases in separation factors. Observed flux improvements are larger than the increase in ion-exchange site density and are attributed to increased mobility of olefins between carrier sites due to the presence of specific surfactants. Results indicate that movement of olefins in Nafion occurs primarily through an interfacial region of the film structure. The ability of a surfactant to improve transport performance is dependent on its ability to partition into the interfacial region. 27 refs., 3 figs., 2 tabs.

• OSTI ID: 6456783
• Journal Information: Chemistry of Materials; (United States), Journal Name: Chemistry of Materials; (United States) Vol. 6:7; ISSN CMATEX; ISSN 0897-4756
• Country of Publication: United States
• Language: English

Related Subjects

30 DIRECT ENERGY CONVERSION
300503 -- Fuel Cells-- Materials
Components
& Auxiliaries
36 MATERIALS SCIENCE
360606* -- Other Materials-- Physical Properties-- (1992-)
ALKANES
ALKENES
DIENES
ELECTROLYTIC CELLS
HEXANE
HEXENES
HYDROCARBONS
MEMBRANES
ORGANIC COMPOUNDS
PERMEABILITY
POLYENES
SURFACTANTS