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Structure–Property Relationships in Hydroxide‐Exchange Membranes with Cation Strings and High Ion‐Exchange Capacity
Author(s) -
Wang Junhua,
Gu Shuang,
Xiong Ruichang,
Zhang Bingzi,
Xu Bingjun,
Yan Yushan
Publication year - 2015
Publication title -
chemsuschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.412
H-Index - 157
eISSN - 1864-564X
pISSN - 1864-5631
DOI - 10.1002/cssc.201501035
Subject(s) - hydroxide , membrane , chemistry , ion exchange , ion , inorganic chemistry , conductivity , oxide , phase (matter) , organic chemistry , biochemistry
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 cm 2 mol −1 for n ≤3; and ∼34 cm 2 mol −1 for n ≥4.