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Purifying of energy carriers methane and hydrogen from CO2 as well as CO2 recovery from mixtures with other gases is a challenging problem for the moment. It is known that glassy polysilicon hydrocarbons – poly(1-trimethylsilyl-1-propyne) [PTMSP] and polyvinyltrimethylsilane [PVTMS] have high CO2 permeability. However, selectivity of CO2 recovery from mixtures of CO2 with Н2 or СН4 is insufficiently high. Therefore, it is of great interest to introduce in polymers groups which are capable for specific interaction with СO2 in order to create materials with high separation selectivity of CO2 -containing gas mixtures. Two ways of preparation of membrane materials on the basis of polysilicon hydrocarbons were taken into consideration: - two-stage chemical modification of PTMSP and PVTMS including synthesis of brominated polymer and subsequent polymer analogous reactions between reactive bromine group with low molecular poly(ethylene glycol) ether (PEG) in the presence of Na for introducing ethylene oxide groups in polymer and with N-butylimidazol and subsequent anion-exchange with potassium hexaflurophosphate (KPF6) for introducing “ionic liquids” moieties; - preparation of mechanical mixtures of PTMSP and PVTMS both with low molecular compounds on the basis of products of interreacting between halogen-containing compounds that have structure like brominated fragment in PTMSP and PVTMS - chloromethyltrimethylsilane (CMTMS) with PEG- and with N-butylimidazol. Sorption properties of modified polymers and mechanical mixtures were studied in order to establish influence of nature and quantity of introduced functional groups and also method of introducing of functional groups in PTMSP and PVTMS (chemical modification or preparation of mechanical mixtures) on ability of reversible interaction with CO2. It was established that it is possible to surpass level of CO2 sorption that is typical for initial PTMSP and PVTMS by introducing groups specific to CO2, and moreover the level of sorption in such materials essentially depends on method of introducing of functional moieties. It was determined that CO2 sorption in chemically modified polymers is higher than that in mechanical mixtures with similar mass composition.