Improved CO2 separation performance of composite membrane with the aids of low-temperature plasma treatment

In this paper, Pebax and Pebax-Tripropionin (TPP) blend multilayer composite membranes were firstly prepared with the aids of low-temperature plasma treatment, and the CO2/N-2 separation properties of the prepared composite membranes were studied. For multilayer composite membranes, PDMS gutter layer was modified with low-temperature plasma of air. The surface properties of the modified PDMS gutter layer (PDMS-plasma) were characterized by contact angle and Fourier transform infrared spectroscopy (FTIR). After treatment, the polar groups were formed on the surface of PDMS and made it hydrophilic, then a defect-free thin Pebax selective layer was successfully formed on PDMS-plasma gutter layer. The CO2 permeance and CO2/N-2 selectivity of Psf/PDMSplasma/Pebax composite membrane were 170 GPU and 49 respectively. Moreover, TPP was blended with Pebax to further enhance the CO2 permeation of the composite membranes, where TPP acted as a plasticizer and hindered the formation of hydrogen bonding in Pebax. The CO2 permeances of Psf/PDMS-plasm/Pebax-TPP blend composite membranes increased greatly with the increase of TPP content. And, the CO2 permeance of Psf/ PDMS-plasma/Pebax-TPP (50 wt%) composite membrane was higher than 400 GPU, which was almost two and half times of that of composite membrane without TPP. The composite membranes prepared in this study showed good CO2/N-2 separation performance.