This paper considers Pebax® MH 1657 as a material for the CO₂/N₂ separating layer in thin film composite (TFC) membranes. The CO₂ permeability of Pebax® can be improved via blending with various poly(ethylene oxide) (PEO) based materials without loss of CO₂/N₂ selectivity. Analogous blends containing PEOs with reactive end groups have been investigated for the possibility of a network formation within the Pebax® matrix. The formation of network is possible through the reaction between two types of additives containing two reactive end groups. The thick film samples and TFC membranes were prepared from mixtures of Pebax® MH 1657, PEG DG526 and JEFFAMINE® with different molecular weights. The samples were characterized by single gas permeation measurements, DSC, and NMR. The samples with incorporated networks show improved and stable gas transport properties compared to the original polymer for both thick films and TFC membranes.