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Modifications of addition poly(5-vinyl-2-norbornene) and gas-transport properties of the obtained polymers
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01.04.2020 |
Wozniak A.
Bermesheva E.
Andreyanov F.
Borisov I.
Zarezin D.
Bakhtin D.
Gavrilova N.
Ilyasov I.
Nechaev M.
Asachenko A.
Topchiy M.
Volkov A.
Finkelshtein E.
Ren X.
Bermeshev M.
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Reactive and Functional Polymers |
10.1016/j.reactfunctpolym.2020.104513 |
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Ссылка
© 2020 Elsevier B.V. Herein four modified polymers were prepared from readily available addition poly(5-vinyl-2-norbornene) (PVNB) and their gas-transport properties were studied in detail. Hydrogenation, epoxidation, cyclopropanation and thiol-en reactions were chosen for the modifications of PVNB. Hydrogenation of PVNB was performed using p-toluenesulfonyl hydrazide. Epoxidation of PVNB was realized employing m-chloroperoxybenzoic acid. Cyclopropanation of PVNB was carried out using diazomethane in the presence of a Pd-catalyst. For thiol-en reaction, thioacetic acid was applied as the source of a thiol and AIBN as an initiator. All listed modifications were performed in high yields (≥80%) without the destruction of polymer main chains. The degree of functionalizations was up to 99%. The influence of these modifications on the properties of the resulting polymers was evaluated. Cyclopropanation and hydrogenation of PVNB led to an enhancement of gas permeability with minimal decrease in selectivity, while epoxidation or thioacetylation gave a substantial increase in CO2/N2 selectivity with decrease in permeability. The modified polymers with polar side-groups exhibited attractive selectivities for CO2/N2, CO2/CH4 and H2/N2 gas separations.
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Stereoselective synthesis and polymerization of Exo-5-trimethylsilylnorbornene
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15.06.2018 |
Alentiev D.
Bermeshev M.
Starannikova L.
Bermesheva E.
Shantarovich V.
Bekeshev V.
Yampolskii Y.
Finkelshtein E.
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Journal of Polymer Science, Part A: Polymer Chemistry |
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10 |
Ссылка
© 2018 Wiley Periodicals, Inc. Herein the stereoselective two-step synthesis of pure exo-5-trimethylsilylnorbornene is reported. The monomer proved to be highly reactive in both metathesis and addition polymerization. ROMP polymerization was catalyzed by the first-generation Grubbs catalyst. High-molecular-weight saturated addition polymers were prepared using nickel or palladium complexes as precatalysts and Na+[B(3,5-(CF3)2C6H3)4]− and/or MAO as cocatalysts. The obtained addition polynorbornenes are highly gas permeable and microporous materials possessing large free volume and BET surface area (up to 540 m2/g). The influence of the substituent orientation (exo- vs. exo-/endo-mixture) on polymer properties was established. The metathesis polymer based on exo-isomer exhibits 1.5- to 2-fold increase of permeability coefficients for all gases in comparison to the similar polymer based on the mixture of exo- and endo-isomers. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018, 56, 1234–1248.
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Optical properties of porous polylactide scaffolds
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01.01.2018 |
Yusupov V.
Sviridov A.
Zhigarkov V.
Shubnyy A.
Vorobieva N.
Churbanov S.
Minaev N.
Timashev P.
Rochev Y.
Bagratashvili V.
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Progress in Biomedical Optics and Imaging - Proceedings of SPIE |
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© COPYRIGHT SPIE. Downloading of the abstract is permitted for personal use only. Light field intensity distribution in three-dimensional polylactide scaffolds after irradiation with low-intensity light from one side of the samples has been determined in the visible and near-infrared regions of the spectrum. Two different types of scaffolds manufactured by the methods of supercritical fluid foaming and surface selective laser sintering have been investigated. The problem is solved by numerical calculation according to the Monte Carlo method involving experimentally obtained information about effective optical parameters of the scaffold material. Information about intensity distribution of the incident light in the matrix volume is needed to assess the radiation level for the scaffold cells after photobiostimulation. It has been shown that the formation of the light field in case of strongly scattering media, such as polylactide scaffolds, is determined by anisotropy g and the scattering coefficient μs.
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