writer：Wei Zhang, Bei Zhang, Guangwei He, Bin Liu, Zhongyi Jiang, Xinlin Yang*, Chenxi Li
keywords：Hollow polymer microspheres, Sulfonated polystyrene brush, Surface-initiated atom transfer radical polymerization, Sulfonated poly(ether ether ketone), Hybrid membrane
source：期刊
specific source：RSC Adv., 5 (7), 5343-5356 (2015). DOI: 10.1039/C4RA13582B
Issue time：2015年

Hollow polymer microspheres grafted with sulfonated polystyrene brushes (HPSS) were synthesized via 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 finally removal of the silica core. These HPSSs were then incorporated into the sulfonated poly(ether ether ketone) (SPEEK) matrix to fabricate hybrid membranes. As a comparison, the SPEEK/HPS hybrid membranes were prepared by incorporation of sulfonated hollow polymer microspheres (HPS) into the SPEEK matrix. The water retention, methanol resistant property 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 SPEEK/HPS hybrid membranes with the same filler contents ranging from 2.5 to 15 wt%. The highest conductivity was obtained as 0.33 S cm^-1 for SPEEK/HPSS under 75 ^oC and 100% relative humidity (RH), which was 83.3% higher than that (0.18 S cm^-1) for SPEEK control membrane under the same conditions. The increment of proton conductivity was mainly contributed to the large cavity of HPSS as water reservoirs and excellent flexibility and high accessibility of the sulfate groups (-SO₃H) pendent on the surface grafted polymer brushes to provide proton hopping sites as proton-conducting pathways. Moreover, the hybrid membranes exhibited good thermal and mechanical stability.