||In this paper, we introduce performance-enhanced, polymeric membranes with free-standing dual-phase property induced by incorporating fillers into polymer matrix. Pre-synthesized graft copolymer, PBE (poly (2-[3-(2H-benzotriazol-2-yl)-4-hydroxyphenyl]ethyl methacrylate)-graft-poly(oxyethylene methacrylate)) was used as filler within the Pebax (poly(amide-b-ether) block copolymer) matrix. Interaction between amphiphilic PBE and PEO part in Pebax permitted formation of CO2-facilitaing nano-channel networks in the membrane. Also, chain-packing of hydrophilic domain inside the Pebax was decreased with the addition of PBE for their interaction, indicating diminished crystallinity, or increased gas transport. Furthermore, ether oxygen and triazole groups in PBE copolymer increased CO2 solubility. As a result, the Pebax/PBE dual-phase membrane exhibited the CO2 permeability of 175.3 Barrer and CO2/N2 selectivity of 48.2 when the content of PBE was 5 wt%, which is better performance of the commercial Pebax membrane (CO2 permeability of 103.3 Barrer and CO2/N2 selectivity of 31.2).