Structure–Property Relationships in Hydroxide‐Exchange Membranes with Cation Strings and High Ion‐Exchange Capacity
Abstract
A series of poly(2,4‐dimethyl‐1,4‐phenylene oxide) hydroxide‐exchange membranes (HEMs) with cation strings containing a well‐defined number of cations (CS‐n) and similar, high ion‐exchange capacities are synthesized to investigate the effect of cation distribution on key HEM properties. As the number of cations on each string grows, the size of the ionic clusters increases from 10 to 55 nm. Well‐connected ion pathways and a hydrophobic framework are observed for n≥4. The enhanced phase segregation increases the hydroxide conductivity from CS‐1 to CS‐6 (30 to 65 mS cm−1) and suppresses the water uptake (from 143 % to 62 %). Moreover, molar hydroxide conductivities for CS‐n membranes show two distinctive stages as n increases: ∼23 S cm2 mol−1 for n≤3; and ∼34 cm2 mol−1 for n≥4.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- Dec 01, 2015
- Source ID
- 10.1002/cssc.201501035
Entities
People
- Bingjun Xu
- Bingzi Zhang
- Junhua Wang
- Ruichang Xiong
- Shuang Gu
- Yushan Yan
Organizations
- Army Research Office
- United States Army Research Laboratory
- University of Delaware