Сrosslinked polymer memranes are obtained by the heat treatment of films prepared from a solution of a mixture of bromine-containing poly(1-trimethylsilyl-1-propyne) (PTMSP) and polyfunctional amine polyethyleneimine (PEI) as a crosslinking agent. Crosslinked products are identified from IR spectra, elemental analysis data, and stability of reaction products to a solvent (CCl4), in which the original brominated PTMSP is soluble. According to the IR spectra, the crosslinking reaction occurs via reactive C–Br bond in bromine-containing PTMSP with the participation of PEI amino groups at a temperature above 90°С. The crosslinking of bromine-containing PTMSP makes it resistant to organic solvents. An increase in the content of PEI in the mixture correlates with the proportion of bromine atoms involved in the reaction. For brominated PTMSP films crosslinked by PEI transport parameters for individual gases and in the mixture n-butane/methane (98.4 mol P_n-C_4H_10 = 12 000 Barrer) and selectivity for n-butane separation from a mixture with methane ( α_n-C_4H_10/CH_4 = 13).

The thermo-oxidative stability and gas transport properties of poly(4-methyl-2-pentyne) (PMP) samples of the mixed configurational composition (50

In this work, functionalization of poly(4-methyl-2-pentyne) (PMP) with quaternary ammonium salts was carried out in order to increase CO2 selectivity in its membrane recovery. The introduction of functional groups was carried out by a two-stage method – bromination of the initial polymer and addition of tertiary alkylamines trimethylamine (TMA) and trimethylamine (TEA). It has been established that the optimal amount of introduced functional groups, while maintaining the mechanical properties of the polymer, is up to 5 mol. %. The results of organoelemental analysis and IR spectroscopy confirm the functionalization reaction of the PMP. X-ray diffraction patterns of the samples indicate an increase in the interchain distance in the series initial PMP–brominated PMP–functionalized PMP. TGA data confirm high thermal and thermal-oxidative stability. The coefficients of permeability, solubility and diffusion of PMP samples containing TMA and TEA salts were determined for individual gases. An increased ideal selectivity for the separation of gas pairs CO2/N2 by 2–3 times and CO2/CH4 by 1.5–2 times has been achieved while maintaining the permeability at a high level.

The effect of the stereoregularity of poly(1-trimethylsilyl-1-propyne) [PTMSP] (cis-content from 50 to 90%) on physical aging was investigated by measurement of the gas permeability. Films from pure PTMSP as well as those with the addition of the antioxidant Irganox 1076 were exposed to the air. The permeability of pure PTMSP films increases with an increase in cis-stereoregularity and correlates with an increase in interchain distances (according to X-ray analysis). For pure PTMSP films, the most significant aging (up to 50% of permeability drop) was observed for polymers with mixed microstructure, and the slowest aging (10–30% of permeability drop) was observed for polymers with cis-regular structure. For PTMSP films with added Irganox 1076, some decrease in permeability with time is also observed. The addition of Irganox 1076 to PTMSP in mixed as well as cis-enriched configurations visibly slows down aging. In the case of cis-regular PTMSP with a slow aging rate, the introduction of an antioxidant does not provide any advantages. The high stability of cis-regular PTMSP demonstrates the possibility of obtaining more stable membrane materials with the highest equilibrium state of the polymer selective layer prepared by casting solution.

In this work, for the first time, we studied the permeability of individual lower hydrocarbons and in a C1/C4 mixture for films based on PTMSP of a new cis-enriched configurational composition (the content of cis-units in the samples was 80 and 90%). The methane permeability of freshly prepared cis-regular PTMSP films (90% of cis-units) exposed to air for a month is higher than the corresponding values of PTMSP films with 80% cis-units. The X-ray diffraction data indicate a looser packing of the cis-regular PTMSP. The introduction of the antioxidant Irganox 1076 into PTMSP films leads to a decrease in the initial level of the methane flux. At the same time, the permeability of films with the addition of Irganox 1076 over time (within 1 month) decreases much more slowly compared to films without the addition of an antioxidant. The permeability of individual lower hydrocarbons through PTMSP films without and with the addition of Irganox 1076 increases in the order С1 C2 C3 C4. The value of the separation factor in the n-butane/methane mixture reaches 33, which is almost 7 times higher than the selectivity for individual components. The high level of n‑butane permeability of cis-enriched PTMSP is maintained for at least a month of films storage in air.

The thermally activated relaxation of poly(1-trimethylsilyl-1-propyne) (PTMSP) samples of various cis-/trans-compositions (50–80% units of cis-configuration) in the presence of phenolic antioxidants of various structures was investigated. It was pointed out that polymers with a high content of cis-units exhibited greater thermal-oxidative stability due to the greater flexibility of the cis-enriched macrochains. The use of hindered phenols as antioxidants made it possible to prevent the process of thermally initiated oxidative degradation. At the same time, the most effective stabilizing agents were antioxidants with larger molecules such as Vulkanox BKF, Irganox 1010, and Irganox 1076. It was shown that the permeability coefficients of stabilized PTMSP during thermal treatment initially slightly decreased (by 20–30%), which, according to the X-ray diffraction data, was associated with an increase in the density of the macrochain packing, and during further heating remained practically unchanged. Note that for the cis-enriched samples, no signs of oxidation or decrease in the transport characteristics were observed during polymer heating for 240 h at 140 °C.

The polymerization of 1-trimethylsilyl-1-propyne mediated by catalytic systems based on Nb and Ta pentafluorides is carried out. Using solid-state 13С NMR spectroscopy, it is shown that the catalysts based on group V metal fluorides possess a well-defined trans-stereoregulating ability and produce trans-enriched polymers compared with analogous samples synthesized using Nb and Ta chlorides and bromides since they have a smaller ligand at the active center of the growing chain. A high trans-stereoregularity of poly(1-trimethylsilyl-1-propyne) is responsible for its insolubility in organic solvents. As evidenced by low-temperature argon sorption, all the synthesized polymers have high BET specific surface area (above 600 m2/g) and micropore volume (above 0.30–0.45 cm3/g). In combination with resistance against organic compounds, this makes them attractive materials for use as fillers of composite membranes and sorbents for the sorption of gases and vapors of organic compounds from streams of commercial mixtures of various composition.

This work is devoted to the chemical modification of the polymers of 1,2-disubstituted acetylenes for the creation of gas-separation membranes possessing enhanced stability to aliphatic hydrocarbons and CO 2 selectivity. The feasibility of obtaining polyacetylenes containing chlorine atoms in the side substituents of poly(1-trimethylsilyl-1-propyne) (PTMSP) and poly(4-methyl-2-pentyne) (PMP) by radical chlorination with N -chlorosuccinimide has been shown. The reaction has been carried out under mild conditions to minimize the possibility of polymer degradation and other side reactions. The obtained polymers exhibit good mechanical and film-forming properties as well as high thermal stability. Chlorinated PTMSP possesses enhanced stability to alicyclic and aliphatic C 5 –C 12 hydrocarbons. It has been shown that in the case of introduction of chlorine into the structure of PTMSP and PMP, the CO 2 /N 2 and CO 2 /CH 4 selectivities increase, with the high level of permeability being retained.

In this work, the polymerization of 1-trimethylsilyl-1-propyne [TMSP] using catalytic systems based on pentabromide Nb(V) and Ta(V) with organometallic cocatalysts Ph3Bi, Ph4Sn, Bu4Sn, Ph3SiH, and Et3SiH was investigated. The use of NbBr5-based catalytic systems has strongly marked cis-stereospecificity and gives highly cis-enriched poly(1-trimethylsilyl-1-propyne) [PTMSP] (content of cis-units above 70%), whereas the use of TaBr5-based catalytic systems leads to the formation of PTMSP with mixed cis-/trans-composition (content of cis-units from 50 to 65%).With increasing cis-content, solvent resistance of PTMSP increases significantly. PTMSP with a content of cis-units above 70% obtained on NbBr5-containing systems in cyclohexane acquires resistance to aliphatic and aromatic hydrocarbons, and cis-regular PTMSP obtained on NbBr5-based systems in toluene is totally insoluble in any of the organic solvents. The results of wide-angle X-ray diffraction indicate an increase in the packing density of the polymer during the transition from a mixed configuration to a cis-regular one. Durable PTMSP film membranes exhibit ultra-high permeability coefficients for individual gases (e.g., $${{P}_{{{{{\text{O}}}_{{\text{2}}}}}}}$$ = 8500–11000 barrer, $${{\alpha }_{{{{{\text{O}}}_{{\text{2}}}}{\text{/}}{{{\text{N}}}_{{\text{2}}}}}}}$$ = 1.5–1.9). According to the low-temperature Ar sorption, PTMSP synthesized with NbBr5- and TaBr5-based catalytic systems has high BET surface areas in the range of 870–1050 m2/g, high intrinsic microporosity, and higher gas permeability coefficients of PTMSP correlate with BET surface area growth.

Fluorinated copolymers with different compositions and geometric structures have been prepared from 1-trimethylsilyl-1-propyne and its fluorinated containing analogue 1-(3,3,3-trifluoropropyldimethylsilyl)-1-propyne and then studied. The copolymers combine resistance to different hydrocarbons with high permeability coefficients and high selectivity of n -butane separation from its mixture with the noncondensable hydrocarbon methane. High microporosity of the copolymers is confirmed by the results of the determination of the pore volume and pore surface area using low-temperature sorption of nitrogen and the investigation of the film surface by atomic force microscopy (AFM). It has been found that microporosity, which determines the transport properties of the copolymers, depends on both their comonomer composition and the microstructure formed at the stage of polymer synthesis catalyzed by a certain catalyst system. In particular, the copolymers produced in the presence of a TaCl 5 –Ph 3 Bi catalyst have a greater pore size and a larger pore surface area relative to copolymers with a similar composition formed in the presence of the NbCl 5 –Ph 3 SiH system. The high values of gas transport parameters of the obtained copolymers and their selectivity for recovery of condensable hydrocarbons from vapor–gas mixtures together with resistance to higher hydrocarbons make these copolymers promising membrane materials, e.g., for use in natural gas conditioning processes or separation of C 3+ hydrocarbons from associated petroleum gas.

Using a NbCl5-based catalyst system, random copolymers of 1-(3,3,3-trifluoropropyldimethylsilyl)-1-propyne and 1-trimethylsilyl-1-propyne are synthesized in a wide range of comonomer contents. The dependences of gas-transport behavior on the composition and supramolecular organization of the copolymer are studied. Composition regions and conditions of preparing copolymers combining high permeability coefficients with resistance against nonpolar organic solvents are ascertained. The copolymers demonstrate a high selectivity in the separation of butane from a methane–butane mixture.

Copolymers of 1-trimethylsilyl-1-propyne (TMSP) with 1-(3,3,3-trifluoropropyldimethylsilyl)1-propyne (TFPS) as part of a systematic series with the TFPS content of the final polymer in the range of 0 to 46 mol % have been synthesized. The resulting samples have been characterized by different instrumental methods including NMR, IR, and DSC techniques. It has been shown that the accessible free volume of the polymer decreases from 30.4 to 19.1% with an increase in the proportion of TFPS units. Moreover, the gas transport properties of the membrane materials are reduced by factors of 30 (oxygen), 50 (nitrogen), and 15 (carbon dioxide), although the selectivity for the O2/N2 and CO2/N2 gas pairs increases from 1.6 to 2.5 and 2.5 to 11.5, respectively. A study of nanofiltration of organic media has shown that the ethanol permeability through the TFPS-co-TMSP copolymer material is reduced by no more than 30%, a value that is comparable with the relative decrease in the fractional free volume of the polymer. An increase in the TFPS content has improved the stability of the membrane material in ethanol (swelling ratio decreased from 61 to 39%), thereby resulting in an increase in the retention of the Orange II anionic dye (350 g/mol) from 89 to 94%.

The homopolymerization of 1-(3,3,3-trifluoropropyldimethylsilyl)-1-propyne under the action of catalytic systems, containing Nb(V) and Ta(V) halides, was studied. Different catalytic systems formed polymers of different microstructures, which had an effect on their morphology and properties. Most catalysts yielded insoluble products. The system NbCl5 – Ph3SiH led to the formation of a soluble film-forming polymer which exhibited high thermooxidative stability, high permeability level and increased permselectivity for some gases. It is essential that both the permeability and the selectivity of poly(1-(3,3,3-trifluoropropyldimethylsilyl)-1-propyne) towards some compounds e.g. CO2 is considerably higher than that of its analog poly(propyldimethylsilyl-1-propyne), which contains no fluorine. This is likely to be caused by specific interactions of particular compounds with fluorine-containing groups of the polymer. The obtained polymer was highly hydrophobic and stable against hydrocarbons, properties that make it a good candidate as a membrane material for the separation of various water–organic mixtures.

Homopolymerization of 1-(3,3,3-trifluoropropyldimethylsilyl)-1-propyne is investigated in the presence of catalysts based on tantalum (V) chloride and niobium (V) pentachloride with various cocatalysts. As a result of homopolymerization, an insoluble polymer is formed. It is established that the insolubility of the homopolymer is connected with the presence in the polymer of “pseudocrystalline” regions playing the role of physical links. Copolymerization of 1(3,3,3-trifluoropropyldimethylsilyl)-1-propyne and trimethylsilyl-1-propyne under the action of the TaCl5-Ph3Bi system is studied. The relative activity constants of monomers, whose ratio points to the formation tendency of copolymers enriched with trimethylsilyl-1-propyne at the early stages of polymerization, are estimated. It is shown that the structures and solubilities of the obtained copolymers depend on their compositions. Gas-transport and hydrophobic-hydrophilic properties for soluble samples are studied. Soluble copolymers have good film-forming properties, improved hydrophobicity, stability against hydrocarbons, and high levels of gas permeability: properties that make them promising materials for the separation of various liquids and gaseous water-organic media.