Enhanced water retention and proton conductivity ofthe proton exchange membranes by incorporating hollow polymer microspheres grafted with sulfonatedpolystyrene brushes
Enhanced water retention and proton conductivity ofthe proton exchange membranes by incorporating hollow polymer microspheres grafted with sulfonatedpolystyrene brushes
复制标题
通过掺入接枝磺化聚苯乙烯刷的空心聚合物微球来增强质子交换膜的保水性和质子电导率
作者：
张伟;张蓓;何光伟;刘斌;姜忠义;杨新林;李晨曦
以SiO2@P（MAA-co-DVB-co-CMSt）核壳微球为原料，通过表面引发苯乙烯原子转移自由基聚合（SI-ATRP）、磺化聚苯乙烯刷（HPSS）、去除二氧化硅核，合成了磺化聚苯乙烯刷（HPSS）接枝中空聚合物微球。然后将这些HPSS掺入磺化聚醚醚酮（SPEEK）基质中以制造杂化膜。作为对比，SPEEK/HPS杂化膜通过将磺化中空聚合物微球（HPS）掺入SPEEK基质中来制备。两种中空聚合物微球的掺杂均提高了聚合物的保水性、耐甲醇性和质子导电性。SPEEK/HPSS杂化膜表现出比SPEEK/HPS杂化膜高得多的质子传导率，具有相同的填料含量范围从2.5至15重量%。在75 °C和100%相对湿度（RH）下，SPEEK/HPSS的最高电导率为0.33 S cm−1，比相同条件下SPEEK对照膜的电导率（0.18 S cm−1）高83.3%。质子传导率的增加主要归因于HPSS的大空腔作为水的水库，和表面接枝聚合物刷上的硫酸根基团（-SO 3 H）的优异的柔性和高可及性，这为质子传导途径提供了质子跳跃位点。此外，杂化膜具有良好的热稳定性和机械稳定性。
Hollow polymer microspheres grafted with sulfonated polystyrene brushes (HPSS) were synthesized via a combination of surface-initiated atom transfer radical polymerization (SI-ATRP) of styrene from SiO2@P(MAA-co-DVB-co-CMSt) core–shell microspheres, sulfonation of the polystyrene brushes, and final removal of the silica core. These HPSSs were then incorporated into a sulfonated poly(ether ether ketone) (SPEEK) matrix to fabricate hybrid membranes. As a comparison, SPEEK/HPS hybrid membranes were prepared by incorporation of sulfonated hollow polymer microspheres (HPS) into a SPEEK matrix. Water retention, methanol resistance and proton conductivity were increased by doping with both kinds of hollow polymer microspheres. The SPEEK/HPSS hybrid membranes exhibited much higher proton conductivity than did the SPEEK/HPS hybrid membranes with the same filler contents ranging from 2.5 to 15 wt%. The highest conductivity was obtained at 0.33 S cm−1 for SPEEK/HPSS under 75 °C and 100% relative humidity (RH), which was 83.3% higher than that (0.18 S cm−1) for a SPEEK control membrane under the same conditions. The increment in proton conductivity was mainly attributed to the large cavities of HPSS acting as water reservoirs, and the excellent flexibility and high accessibility of the sulfate groups (–SO3H) on the surface grafted polymer brushes, which provide proton hopping sites for proton-conducting pathways. Moreover, the hybrid membranes exhibited good thermal and mechanical stability.