Chemistry

Rigid rod poly(p-phenylene sulfonic acid) PEMs: High conductivity at low relative humidity due to "frozen-in-free volume"

Document Type

Conference Proceeding

Abstract

The advantage of using linear rigid-rod liquid crystalline materials as polyelectrolytes is that they must pack parallel. If a small mole fraction of comonomer with a large cross-sectional area is inserted, several will hit neighboring molecules before the chains can touch, increasing the distance between molecules over their whole length. This generates nanopores lined with acid groups. Water is held tightly because of capillary attraction and H-bonding; the structure can shrink only by high energy bending of the molecules, i. e. "frozen in free volume". Work has focused on poly(p-biphenylene 3, 3′-disulfonic acid) (PBPDSA) and poly(p-phenylene 2, 5-disulfonic acid) (PPDSA) homopolymers and their copolymers. Alkylbenzene groups were grafted on the backbones using polyphosphoric acid to make water insoluble polymers. Water is held very strongly at low humidity leading to exceptionally high conductivity; PPDSA σ is 100 mS at 75°C and 15% RH. Water insoluble graft copolymer conductivities are lower, but still extremely high. Dimensional stability of PBPDSA grafts is very good but conductivities are lower than those of the PPDSA grafts. ©The Electrochemical Society.

Publication Title

ECS Transactions

Publication Date

12-2010

Volume

33

Issue

1 PART 1

First Page

695

Last Page

710

ISSN

1938-5862

ISBN

9781566778206

DOI

10.1149/1.3484565

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