Abstract:

The effects of main chain element types on the properties of polymer proton exchange membranes with low degree of sulfonation were explored through changing the kinds of comonomers. 3,3’-disulfonic acid sodium salt-4,4’-difluorodiphenyl sulfone was a sulfonated monomer, 4,4’-difluorodiphenyl sulfone was a non-sulfonated monomer, 4,4’-Dihydroxy diphenyl ether or 4,4’-dimercaptodiphenyl sulfide was a comonomer, and the sulfonated aromatic copolymer having a sulfonation degree of 30% and 50%, respectively, can be controlled by a nucleophilic polycondensation reaction. A transparent and tough proton exchange membrane was prepared by the solution casting method. Systematic characterizations and measurements suggested that both polymer membranes showed good mechanical properties as well as moderate water absorption and swelling. The two polymer proton exchange membranes had an initial decomposition temperature of 250℃ and good thermal stability. With the increase of the degree of sulfonation, the water absorption, swelling ratio and proton conductivity of the two polymer membranes increased. Since the main chain sulfur was more conjugated to the oxygen atom and the benzene ring and the interaction between the electron donating sulfur atom and the electron withdrawing group, the SPTES membrane exhibited a higher glass transition temperature (T _g) than the SPES membrane, and a lower swelling ratio and higher proton conductivity. The proton conductivity of SPES-50 and SPTES-50 were 0.136S/cm and 0.142S/cm at 80℃ and 100% RH, respectively. SPES-50 and SPTES-50 membranes all could be applied as promising PEMs for fuel cells. This study may contribute to the rational design of proton-conducting materials.

Key words: sulfonated aromatic copolymer, nucleophilic condensation, proton conductivity, proton exchange membrane

摘要：

通过改变共聚单体种类，探究主链元素种类对聚合物质子交换膜性能的影响。以3,3'-二磺酸基钠盐-4,4'-二氟二苯砜为磺化单体，4,4'-二氟二苯砜为非磺化单体，4,4'-二羟基二苯醚或4,4'-二巯基二苯硫醚为共聚单体，通过亲核缩聚反应成功可控制备出磺化度分别为30%和50%的磺化聚芳醚砜（SPES）与磺化聚芳硫醚砜（SPTES）。采用流延法制备了两种聚合物的透明坚韧的质子交换膜。研究发现两种聚合物膜均显示出了良好的力学性能以及较为适中的吸水率与溶胀度。两种聚合物质子交换膜的起始分解温度达到250℃，具有良好的热稳定性。随磺化度的升高，两种聚合物膜的吸水率、溶胀率以及质子传导率均升高。由于主链硫较氧原子与苯环的共轭作用更强以及供电子硫原子与吸电子基团的相互作用，SPTES膜较SPES膜表现出更高的玻璃化转变温度（T _g）、更低的溶胀率以及更高质子传导率。其中SPES-50与SPTES-50在80℃、100%RH条件下，质子传导率分别为0.136S/cm与0.142S/cm，表明其作为质子交换膜具有潜在的应用前景。

关键词: 磺化芳香族共聚物, 亲核缩聚, 质子传导率, 质子交换膜