Abstract: Three types of rigid-group-bridged polysiloxanes-modified ethylcellulose （EC） mixed membranes were prepared by using three bridged-polysiloxanes with different rigid groups of hexafluoroimide， naphthalimide， and fluorene as modifiers and EC as a substrate， through solution co-blending and coating. The three mixed membranes exhibited a good film formation ability， high mechanical properties， and good thermal stability. Compared to pure EC membrane， the three mixed membranes gained an improvement in the permeability of CO2 without sacrificing selectivity （CO2/N2 and CO2/CH4）. Especially， the naphthalimide bridged-polysiloxanes obtained a CO2 permeation coefficient of over 213 barrers， which is 4.9 times higher than pure EC membrane.

Key words: bridged-polysiloxanes, ethyl cellulose, mixed membrane, gas separation