Two organosilica presursors,1,4-bis(triethoxysilyl)benzene(BTESB)with benzene bridges and 4,4'-bis(triethoxysilyl)biphenyl(BTESBPh)with biphenyl bridges were utilized for the fabrication of organosilica membranes via the sol-gel strategy.The two membranes were applied to the gas separation.At 25℃,BTESB membrane displayed a C3H6 permeance of 3.4×10-9mol/(m2·s·Pa)and C3H6/C3H8 selectivity of 9.6.Nevertheless,BTESBPh membrane showed a C3H6 permeance of 1.7×10-8mol/(m2·s·Pa)and a comparable C3H6/C3H8 selectivity of 10.5.BTESBPh membrane networks with biphenyl bridged structures were much looser and could achieve higher gas permeance.The π-π interactions occurred between the big π bond in the benzene ring and the C== C bond in the C3H6 molecules,which was beneficial for the preferential adsorption and permeation of the C3H6 molecules.The biphenyl bridges in BTESBPh membranes enhanced the adsorption and permeation process,as evidenced by the increased C3H6/C3H8 selectivity of the BTESBPh membrane under low testing temperatures.This study could provide a reference for the development of high-performance propylene/propane separation membranes.
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