SPEEK/PES-C、SPEEK/SPES-C共混质子交换膜研究

通过在磺化聚醚醚酮(SPEEK,DS=61.68%)中分别混入酚酞型聚醚砜(PES-C)、磺化酚酞型聚醚砜(SPES-C,DS=53.7%)制备出SPEEK/PES-C、SPEEK/SPES-C共混质子交换膜.结果表明,共混的两种聚合物之间均具有较好的相容性.PES-C、SPES-C的混入能有效降低膜的溶胀及甲醇透过,且随着共混量的增加,这种作用越趋明显.纯SPEEK膜在75℃左右溶解,而SPEEK/PES-C(30wt%)、SPEEK/SPES-C(30wt%)共混膜在80℃时溶胀度仅为22.5%、26.32%.在室温至80℃范围内,纯SPEEK及共混膜的甲醇透过系数都在10-7cm2.s-1数量级上,远小于Nafion115膜.在饱和湿度下,温度大于90℃时,SPEEK/PES-C(20wt%)共混膜电导率超过Nafion115膜;温度大于110℃时,SPEEK/SPES-C(30wt%)共混膜电导率与Nafion115膜相当,达到0.11S.cm-1.高电导率,低透醇系数以及明显提高了的可使用温度表明该类共混膜有望在DMFC中使用.

STUDIES ON SPEEK/PES-C AND SPEEK/SPES-C BLEND PROTON-EXCHANGE MEMBRANES

Sulfonated poly(ether ether ketone)(SPEEK)is a very promising alternative membrane material for direct methanol fuel cells(DMFC).The demand of high proton conductivity calls for the membranes to have a high degree of sulfonation(DS)and work at elevated temperatures.However,with a fairly high DS,SPEEK membrane can swell excessively and even dissolve at high temperatures.To deal with this contradictory situation,phenolphthalein poly(ether sulfone)(PES-C)and sulfonated phenolphthalein poly(ether sulfone)(SPES-C,DS=53.7%)were respectively blended into SPEEK polymer to prepare SPEEK/PES-C and SPEEK/SPES-C blend membranes.DSC results revealed that the two blended polymers showed good miscibility.The effect,that both PES-C and SPES-C can decrease effectively the swelling degree and methanol permeability of blend membranes,became evident with the increment of PES-C and SPES-C contents.Pure SPEEK membrane dissolved completely at 75℃,however,the swelling degree of SPEEK/PES-C(30%)and SPEEK/SPES-C(30%)were 22.5% and 26.32% at 80℃,respectively.From room temperature to 80℃,the blend membranes presented methanol permeability of around 10-7 cm2·s-1,which was about one order of magnitude lower than that of Nafion  115.Under 100% relative humidity,the proton conductivity of blend membranes with 20 wt% PES-C exceeded that of Nafion  115 above 90℃,the proton conductivity of blend membranes with 30 wt% SPES-C reached 0.11 S·cm-1 of Nafion  115 at 110℃.The blend membranes are promising for DMFC application because of their improved applicable temperature,high conductivity and low methanol permeability.