Structure⁃activity relationship of polysulfone cation exchange membrane for methanol fuel cells

doi:10.19491/j.issn.1001-9278.2022.05.011

Abstract

Abstract:

Chloroprene polysulfone and chloroprene polysulfone were prepared through an acylation reaction， and then pyrene sulfonic acid polysulfones with different side chain lengths （4PS?SA and 5PS?SA） were prepared through a nucleophilic substitution reaction with 8?hydroxy?1，3，6?pyrene trisodium as a reagent. A series of 4PS?SA and 5PS?SA cation exchange membranes were prepared using a solution?casting method. The chemical structures， bonding amount of sulfo?nic acid groups， and effect of flexible side chains on the performance of pyrene sulfonic acid polysulfone cation exchange membranes were investigated using an infrared spectrometer， a UV?visible spectrophotometer， a nuclear magnetic resonance instrument， and an atomic force microscope. The result indicated that 4PS?SA and 5PS?SA cation exchange membranes exhibited an excellent dimensional stability and methanol resistance， and their water absorption rate， water swe?lling rate， and proton conductivity increased with an increase in temperature. The 5PS?SA with a longer side chain exhibi?ted a better dimensional stability and proton conductivity at the same ion exchange capacity. The 5PS?SA?3 showed water sorption rates of only 23.7 % and 39.1 % at room temperature and 85 oC， respectively. Its proton conductivities were 0.093 S/cm at room temperature and 0.142 S/cm at 85 oC， and its methanol permeability was only 7.09×10^-7cm²/s. These results indicated that the polysulfone cation exchange membranes had good comprehensive performance and were expected to be used for cation exchange membrane fuel cells.

Key words: flexible side chain, acylation reaction, cation exchange membrane, dimensional stability

CLC Number:

TQ326.55

QIAO Zongwen, DENG Jiaqi, JI Wei. Structure⁃activity relationship of polysulfone cation exchange membrane for methanol fuel cells[J]. China Plastics, 2022, 36(5): 62-67.

Figures/Tables 8

Fig.1. Reaction equation for preparation of 4PS?SA and 5PS?SA

Fig.2. FTIR spectra of the samples

Fig.3. 1H?NMR spectra of the samples

Fig.4. Water absorption rate?temperature curves of the samples

样品	BA/ mmol·g^-1	IEC/ mmol·g^-1	质量保留率/ %	甲醇扩散系数/ ×10⁷cm²·s^-1
4PS⁃SA⁃1	0.97	0.97	99.2	4.13
4PS⁃SA⁃2	1.27	1.27	98.6	6.31
4PS⁃SA⁃3	1.42	1.42	98.1	7.89
5PS⁃SA⁃1	0.98	0.97	99.5	4.07
5PS⁃SA⁃2	1.28	1.28	98.9	5.28
5PS⁃SA⁃3	1.42	1.42	98.3	7.09
Nafion115	—	0.90	98.0	16.80

Tab.1. Properties of 4PS?SA and 5PS?SA cation exchange membranes

Fig.5. Swelling rate?temperature curve of the samples

Fig.6. AFM images of the samples（500 nm×500 nm）

Fig.7. Proton conductivity?temperature curve of the samples

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