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Polysulfones grafted with poly(vinylphosphonic acid) for highly proton conducting fuel cell membranes in the hydrated and nominally dry state

Parvole, Julien LU and Jannasch, Patric LU (2008) In Macromolecules 41(11). p.3893-3903
Abstract
Mechanically strong and flexible membranes with very high local concentrations of immobilized proton-conducting phosphonic acid have been achieved by grafting poly(vinylphosphonic acid) side chains onto polysulfones. The graft copolymers were prepared by anionic polymerization of diethyl vinylphosphonate initiated from lithiated polysulfones, followed by quantitative cleavage of the ester functions. The resulting phosphonic acid units acted like monoprotic acids to indicate a high level of intramolecular interactions, and the phase-separated nature of the copolymers was shown by dual glass transitions. Fully polymeric membranes were conveniently cast from solution and showed high proton conductivities, e.g., 5 mS/cm under nominally dry... (More)
Mechanically strong and flexible membranes with very high local concentrations of immobilized proton-conducting phosphonic acid have been achieved by grafting poly(vinylphosphonic acid) side chains onto polysulfones. The graft copolymers were prepared by anionic polymerization of diethyl vinylphosphonate initiated from lithiated polysulfones, followed by quantitative cleavage of the ester functions. The resulting phosphonic acid units acted like monoprotic acids to indicate a high level of intramolecular interactions, and the phase-separated nature of the copolymers was shown by dual glass transitions. Fully polymeric membranes were conveniently cast from solution and showed high proton conductivities, e.g., 5 mS/cm under nominally dry conditions at 120 °C and up to 93 mS/cm under 100% relative humidity at the same temperature. The corresponding conductivities measured for Nafion 115 under the same conditions were 0.04 and 105 mS/cm, respectively. The former membranes furthermore showed high thermal stability with decomposition temperatures exceeding 300 °C under air. Additions of 2−5 wt % of a perfluorosulfonic acid polymer to the phosphonated membranes were found to reduce the water uptake significantly, thus improving the mechanical properties. The conductivity of these fully polymeric doped membranes was generally observed to be enhanced, or at least to remain at the same level, under both humidified and nominally dry conditions. The findings of this study demonstrate that phosphonated membranes with a proper macromolecular design may potentially show some important advantages in relation to the more commonly studied sulfonated membranes in fuel cell applications. (Less)
Please use this url to cite or link to this publication:
author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Macromolecules
volume
41
issue
11
pages
3893 - 3903
publisher
The American Chemical Society
external identifiers
  • wos:000256393500024
  • scopus:45849134562
ISSN
0024-9297
DOI
10.1021/ma800042m
language
English
LU publication?
yes
id
4a5de6cb-1675-4270-8bb7-90c0c91cd2bf (old id 1150184)
alternative location
http://pubs.acs.org/cgi-bin/abstract.cgi/mamobx/asap/abs/ma800042m.html
date added to LUP
2008-06-30 12:19:45
date last changed
2017-10-01 03:48:54
@article{4a5de6cb-1675-4270-8bb7-90c0c91cd2bf,
  abstract     = {Mechanically strong and flexible membranes with very high local concentrations of immobilized proton-conducting phosphonic acid have been achieved by grafting poly(vinylphosphonic acid) side chains onto polysulfones. The graft copolymers were prepared by anionic polymerization of diethyl vinylphosphonate initiated from lithiated polysulfones, followed by quantitative cleavage of the ester functions. The resulting phosphonic acid units acted like monoprotic acids to indicate a high level of intramolecular interactions, and the phase-separated nature of the copolymers was shown by dual glass transitions. Fully polymeric membranes were conveniently cast from solution and showed high proton conductivities, e.g., 5 mS/cm under nominally dry conditions at 120 °C and up to 93 mS/cm under 100% relative humidity at the same temperature. The corresponding conductivities measured for Nafion 115 under the same conditions were 0.04 and 105 mS/cm, respectively. The former membranes furthermore showed high thermal stability with decomposition temperatures exceeding 300 °C under air. Additions of 2−5 wt % of a perfluorosulfonic acid polymer to the phosphonated membranes were found to reduce the water uptake significantly, thus improving the mechanical properties. The conductivity of these fully polymeric doped membranes was generally observed to be enhanced, or at least to remain at the same level, under both humidified and nominally dry conditions. The findings of this study demonstrate that phosphonated membranes with a proper macromolecular design may potentially show some important advantages in relation to the more commonly studied sulfonated membranes in fuel cell applications.},
  author       = {Parvole, Julien and Jannasch, Patric},
  issn         = {0024-9297},
  language     = {eng},
  number       = {11},
  pages        = {3893--3903},
  publisher    = {The American Chemical Society},
  series       = {Macromolecules},
  title        = {Polysulfones grafted with poly(vinylphosphonic acid) for highly proton conducting fuel cell membranes in the hydrated and nominally dry state},
  url          = {http://dx.doi.org/10.1021/ma800042m},
  volume       = {41},
  year         = {2008},
}