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Volume 08
Innovative Energy & Research
ISSN: 2576-1463
Advanced Energy Materials 2019
July 11-12, 2019
July 11-12, 2019 | Zurich, Switzerland
21
st
International Conference on
Advanced Energy Materials and Research
Novel polyolefin-based proton exchange membranes for fuel cell applications
T C Mike Chung
The Pennsylvania State University, USA
A
new class of polyolefin based proton exchange membranes are formed by a well-defined graft copolymer that
contains a high molecular weight semicrystalline PE or PVDF backbone and several amorphous sulfonated
poly(arylene ether sulfone) (s-PAES) or sulfonated polystyrene (s-PS) side chains. The suitable chemical routes
will be discussed for preparing the graft copolymers with desirable backbone molecular weight, graft density, graft
length, sulfonic acid concentration, etc. One example is PE-g-s-PAES copolymer that is prepared by a graft onto
reaction between high molecular weight HDPE with few benzyl bromide groups and poly(arylene ether sulfone)
(PAES) with two terminal phenol groups. The resulting PE-g-PAES graft copolymer was solution cast into uniform
film (thickness 20–40 μm), followed by a heterogeneous sulfonation reaction to obtain PE-g-s-PAES PEMs. The
unique combination of hydrophobicity, semicrystallinity and high molecular weight of PE backbone offers PEM
with a stable (non swellable) matrix. On the other hand, the hydrophilic proton conductive s-PAES side chains in the
PE-g-s-PAES membrane self-assemble into many conducting channels. In addition, a thin PE layer spontaneously
formed on the membrane surfaces. In the bulk, these membranes show good mechanical properties (tensile strength
>30 MPa, Young’s modulus >1400 MPa) and low water swelling (λ <15) even with high IEC >3 mmol/g in the s-PAES
domains. Compared to Nafion 117, most PE-g-s-PAES PEMs show similar hydration numbers (λ <15) but higher
proton conductivity (up to 160 mS/cm). More interestingly, all PE-g-s-PAES PEMs show higher through-plane
conductivity than in-plane conductivity. In direct methanol fuel cells, the PE surface layer also minimizes methanol
cross over from anode to cathode with reduced fuel loss, and stops the HO• and HO
2
• radicals, originally formed
at the anode, entering PEM matrix. Overall, this newly developed PE-g-s-PAES membrane offers a combination of
desirable properties, including conductivity, water uptake, selectivity, mechanical strength, and cost-effectiveness for
fuel cell applications.
chung@psu.eduInnov Ener Res 2019, Volume 08