OCH3 CH3O

NN

O CH3

SO3-Na

O

NN

ON

NN

CH3

SO3-Na

ON

NN

CH3

SO3-Na

SO3-Na

m l x yO

N

NN

CH3CH3 ON

NN

CH3

SO3-Na

o p

ASAXS characterization of functionalized polyoxadiazoles and polytriazoles

ResultsResults

Mariela L. Ponce1, Dominique Gomes1, G. Goerigk2, Suzana P. Nunes1

1Institute of Polymer Research, GKSS Research Centre Geesthacht GmbH, Max-Planck-Str. 1, 21502 Geesthacht2Institute of Solid State Research, Forschungszentrum Jülich, D-52425 Jülich

E -mail: mariela.ponce@gkss.de

The fuel cell group at GKSS is now investigating sulfonated polyoxadiazoles (SPOD) and polytriazoles (SPT) containing high concentration of basic nitrogen atoms in

the repeating unit besides the sulfonic group, which give them many sites for the proton conduction and making them very promising polymeric materials for fuel cells

operation at 150-250°C in a low humidity environment. ASAXS was chosen as a convenient method to evaluate the arrangement of sulfonic groups, in order to figure out

how their distribution influences the proton transport.

ReferencesReferences1. D. Gomes, J. Roeder, M.L. Ponce, S.P. Nunes; J. Mem. Sci. 295 (2007) 121–1292. M.L. Ponce, D. Gomes, S.P. Nunes, J. Mem. Sci. submitted

3. D. Gomes, I. Buder, S. P. J. Polymer Sci., Part B: Polymer Physics 44(16) (2006) 2278-229 4. D. Gomes, J. Roeder, M.L. Ponce, S.P. Nunes; J. Power Sources 175 (2008) 49-595. G. Goerigk, M. L. Ponce, D. Gomes, S. P. Nunes, HASYLAB Jahresbericht 46 (2006) 1183-1184

AcknowledgementsAcknowledgementsThis work was developed in the frame of the Virtual Institute

on Asymmetric Structures for Fuel Cell sponsored by the

Helmholtz Association.

IntroductionIntroduction

SPT polymer structure

The total scattering curves of SPT and SPOD with similar sulfonation degree (Figure 1) show the characteristic broad maximum of the ionomer peak (q = 3.0 nm -1).

For both polymers a correlation length of 2.1 nm can be estimated, indicating that the distances between ion clusters are similar. The upturn in intensity at q < 0.1 nm-1 can

be attributed to larger inhomogeneities.

From the scattering pattern of SPT and POD membranes with different sulfonation level (Fig. 2 and 3), it can be assumed that there is no change in the intercluster

distance as a function of the ion content (SPT, q = 3 nm-1; SPOD, q = 3.5 nm-1). Just the change in the relative intensity of the scattering pattern is due to a change in the

concentration of aggregate particles. The higher relative intensity at low q for the SPOD12Rx and SPT3Rx, relative to the plain SPOD and SPT polymers, respectively, are

attributed to particle aggregation after addition of 5 wt.% of sulfonated silica into the polymer. Similar results have been observed by us when these particles were added to

a sulfonated poly(ether ether ketone) matrix [5].

ExperimentalExperimental All the polymers used to prepare the membranes were synthesized at GKSS [1-4]; the membrane samples were treated with a RbCl solution to exchange protons by

Rb+. The ASAXS measurements were performed at the JUSIFA beamline at DESY-HASYLAB, Hamburg, in the energy range of the K-absorption edge of Rb at 15200 eV.

0,1 10,01

0,1

1

10

d/d

[cm

-1]

q [nm-1]

SPOD (S/C: 0.092) SPT (S/C: 0.091)

0,1 10,01

0,1

1

10

100

d/d

[cm

-1]

q [nm-1]

SPT (S/C: 0.091) SPT (S/C: 0.094) SPT (S/C: 0.076) SPT3xR (S/C: 0.093)

0,1 10,01

0,1

1

10

100

d/d

[cm

-1]

q [nm-1]

F3 SPOD (S/C: 0.092) SPOD (S/C: 0.149) SPOD12Rx (S/C: 0.148)

POD polymer structure

Figure 1. Total scattering curves of SPT and SPOD

membranes

Figure 2. Total scattering curves of SPT membranes Figure 3. Total scattering curves of SPOD membranes