Gas-permeation properties of sandwich-like polyaniline/poly(ethylene vinyl acetate) nanocomposite membranes

•PANI with 2D leaf structure and sandwich structure was successfully synthesized.•Fillers with 2D layered structure improved more in decreasing diffusivity in gas membrane separation.•The selectivity of membrane gas separation of CO2/N2 was increased to about 32 with permeability of CO2 at 97.5 barrer as the nanocomposite membrane contained 3wt% S-PANI. The effect of the use of sandwich-like polyaniline (S-PANI) nanocomposites in CO2 gas-separation membranes was investigated. S-PANI nanocomposites were synthesized via a two-step dispersion polymerization method. The first step was to manufacture a leaf-like polyaniline (L-PANI), which was used in the next step as a 2D template to synthesize the S-PANI. SEM images show that a three-layer sandwich-like structure of the S-PANI was successfully synthesized. ATR-FTIR measurements revealed that the S-PANI has a structure with conductive PANI layers on both sides of the L-PANI template. Furthermore, the N2 and CO2 adsorption isotherms illustrate that S-PANI is much more attractive to CO2 than N2 because of the amine functional groups of S-PANI. Hence, the CO2/N2 separation performance of the ethylene vinyl acetate (EVA) copolymer membrane was successfully enhanced by the addition of the S-PANI nanocomposite. The CO2/N2 selectivity of the membrane increased from 6.8 to 32.5 with a 3-wt% loading of S-PANI within the EVA matrix. The results show that 2D S-PANI could feasibly be used for CO2 gas membrane separation.