TECHNOLOGY FOCUS - POLYMERS - Preferred Components: The hard polymeric blocks are polyurethane blocks, polyamide blocks, non-amorphous polyester blocks, polyimide blocks, polysulfone blocks and/or polycarbonate blocks. The soft polymeric blocks are polyether blocks, amorphous polyester blocks or polysiloxane blocks. The multi-block thermoplastic elastomer is a polyamide-polyether multi-block copolymer comprising a multi-block thermoplastic elastomer comprising a polyamide block as the hard block and a polyether block as the soft block, which is substituted polyamide-polyether compounds of formulae ((-C(=O)-P1-C(=O)-O-Q-O-)y) (VII), (R5-(C(=O)-D1-C(=O)-O-PE-O-(C(=O)-X-C(=O)-O-PE-O-)a)b-R6) (VIII) and (R5-(C(=O)-D2-(C(=O)-O-PE-O-C(=O)-D2)c-C(=O)-NH-X1-NH-)d-R6 (IX). The polymer comprising a metal of group 14 of the periodic system of the elements, comprises: (a) substituted polysiloxane compounds of formula ((R1)3-M-O-((R1)2-M-O)p-((R1)-M(R2)-O)q-M-(R1)3) (I); (b) substituted polyalkyne compounds of formula ((R1)2-M(R3)-((-)C=C(R4))r-) (II); (-(C(R1)=C(R1))s-(C(R1)=C-M(R1)2(R3))t-) (III); (R1)2-M(R3)-A-(-(C=C(R4))u-) (IV); and (-(C(R1)=C(R1))v-(C(R1)=C(A-M(R3)(R1)2))w-) (V); and (c) substituted polyalkene compounds of formula (VI). The polyoxyalkylene chain is a polyoxyethylene chain. The weight average molecular weight (Mw) of the polysiloxane (I), the polyalkynes (II)-(V) or the polyalkene (VI) is determined by the polyoxyethylene chain of 60-90%. The polyoxyethylene chain is of formula (-(CH2-CH2-CH2-O)-(-CH2-CH2-O)p-CH3). The membrane comprises 0.1-99 wt.% of the polymer comprising a metal of group 14 of the periodic system of the elements, based on the total weight of the membrane. The membrane comprises 1-99.9 wt.% of the multi-block thermoplastic elastomer comprising alternating hard polymeric blocks and soft polymeric blocks. The membrane has a carbon dioxide gas permeability coefficient of at least 120 Barrer. The membrane comprises a support.P1 = polyamide block;Q = a polyether block;n = an integer such that the intrinsic viscosity eta of the multi-block thermoplastic elastomer is 0.5-2.5;R5, R6 = OH and/or H;a = 0.1-10;b, d = 2-50;c = 1-4;D1 = a residue of an oligoamidediacid or a diacid having a number average molecular weight (Mn) of 300-8000;D2 = a residue of an oligoamidediacid having a number average molecular weight (Mn) of 300-3000;PE = a residue of a polyoxyalkylene, preferably a polyoxyethylene (having a Mn of 200-5000);X = a residue of a diacid comprising aliphatic, cycloaliphatic or aromatic hydrocarbon residues having 4-12C;X1 = a residue of a diacid comprising aliphatic, cycloaliphatic or aromatic hydrocarbon residues having 4-20C;M = group 14 metal;R1 = 1-12C alkyl and/or 6-12C aryl;R2 = polyoxyalkylene chain;p = 5-5000;q = 5-10000;R3 = R1 or polyoxyalkylene chain;R4 = H, 1-12C alkyl, (-CH2M(R1)3), and/or -MR3(R1)2;r, u, x = 100-20000;(s/(s+t)), (v/(v+w)) = greater than or equal to 0.2;(t/(s+t)), (w/(v+w)) = greater than or equal to 0.05;A = (-(C(R1)2)v1-);v1 = 1-6; andp = is in such a range that the Mn of the polyoxyethylene chain is less than or equal to 1000. EXAMPLE - To a solution of Pebax MH 1657 (RTM: Polyether block amide) (3 wt.% ) in a mixture of ethanol/water (70/30 wt/wt) was prepared under reflux at 80 degrees C under continuous stirring (2 hours). After complete dissolution of the polymer, the solution was cooled to ambient temperature. Subsequently, different amounts of polydimethylsiloxane-graft-poly(ethylene glycol) (PDMS-g-PEG) were added and the solution was stirred for 1 more hours. The solution was poured in a petri dish and placed under a nitrogen atmosphere at ambient temperature to evaporate the solvent. The obtained films were dried in a vacuum oven at 30 degrees C to remove residual solvent, to give the membrane.