CO 2 capture by polymeric membranes composed of hyper-branched polymers with dense poly(oxyethylene) comb and poly(amidoamine)

Due to CO 2 -philic nature of polyoxyethylene (POE), a dense POE comb structure was tethered onto PMMA backbone to develop CO 2 separation membranes over N 2 . The resulting hyper-branched polymers displayed preferential CO 2 permeation. When the polymer thin layer was formed on a high gas permeable polydimethylsiloxane (PDMS) support by a spray-coating manner, the resulting thin film composite (TFC) membranes displayed very high CO 2 permeability. However, the CO 2 selectivity, which was the permeability ratio of CO 2 over N 2 , was moderate and lower than 50. To enhance the selectivity, poly(amidoamine) (PAMAM) was introduced to the hyper-branched polymers in the CO 2 -selective layer of the TFC membranes. The CO 2 selectivity increased from 47 to 90 with increasing PAMAM content to 40 wt%, and it was drastically enhanced to 350 with PAMAM content of 50 wt%. Differential scanning calorimetry (DSC) and laser microscope revealed formation of PAMAM-rich domain at the higher amine content, where CO 2 could readily migrate in comparison to the other polymeric fractions.