Dimethylformamide dmf

The poly(propylene oxide) (PPO)-based polyurethane prepolymer (PUR) containing three isocyanate terminal groups with an average molecular weight (MW) of 3500 g/mol was supplied by Fabrires—Produtos Químicos S.A., Lisbon, Portugal. Tris(hydroxymethyl)aminomethane (TRIS) (purity ≥ 99.8%) and methyl-beta-cyclodextrin (MBCD, MW = 1303.3 g/mol) were provided by Sigma-Aldrich (St. Louis, MO, USA). Congo red (CR) (purity > 98.0%) was provided by Tokyo Chemical Industry Co., Ltd., Tokyo, Japan and dimethylformamide (DMF) (p.a. grade, 99.8%) provided by Panreac (Barcelona, Spain) was used as a solvent. Gas permeation experiments and gas solubility measurements were carried out using carbon dioxide (purity ≥ 99.98%) and oxygen (purity ≥ 99.5%), all supplied by Air Liquide (Lisbon, Portugal).

Two prepolymers were used for the synthesis of the polyurethane membranes: (i) a poly(propylene oxide) (PPO) based polyurethane prepolymer with three isocyanate terminal groups (PUR), supplied by Fabrires-Produtos Químicos S.A. (Lisbon, Portugal) and (ii) a polycaprolactone diol prepolymer (PCL-diol), supplied by Sigma-Aldrich (Lisbon, Portugal) with a stated molecular weight of 530 Da. The solvents used were dimethylformamide (DMF) (p.a. grade, 99.8%) and diethyl ether (DEE) (p.a. grade, 99.5%) provided by Panreac (Barcelona, Spain). The catalyst used was Tin(II) 2-etilhexanoate (p.a. grade, 95%) provided by Sigma-Aldrich (Lisbon, Portugal).
Gas permeation experiments and gas solubility measurements were carried out using nitrogen (purity ≥ 99.999%), carbon dioxide (purity ≥ 99.98%) and oxygen (purity ≥ 99.5%), all supplied by Air Liquide (Lisbon, Portugal).