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New bis-trimethylsilyl-substituted poly(tricyclo[4.2.2.02,5]deca-3,9-diene) (PTDDSi2) and poly(tricyclo[4.2.2.02,5]deca-3,7,9-triene) (PTDTSi2) were synthesized by ring-opening metathesis polymerization of the corresponding new monomers in the presence of 1st ‒ 3d generation Grubbs' catalysts. For monomer synthesis, the reaction of chlorosilanes with 1,3,5,7-cyclooctatetraene was studied for the first time. Polymerization conditions (catalyst type, temperature, monomer concentration) were selected to provide 77–96% yield of polymers. The monomer and polymer spatial structure had a significant effect both on their synthesis and on properties. The high Т g of PTDDSi2 (above the T d), as well as the easily proceeding retrodiene decomposition of the PTDTSi2 with the formation of bis(trimethylsilyl)benzene and polyacetylene (at 98 °C) indicated high rigidity of the polymer chain. A gas permeability investigations of mono-(PTDDSi), bis-Me 3 Si-substituted PTDDSi2 and hydrogenated product H-PTDDSi2 showed that PTDDs belong to the group of polymers with moderate gas permeability (P O2 up to 100 Barrer). Nonetheless, PTDDSi2 exhibited "solubility controlled permeability", which is unusual for moderately permeable polymers. [Display omitted] • New silicon-substituted monomers and polymers based on cyclooctatetraene were synthesized. • Steric factors were found to play an important role in the synthesis of the monomers and polymers studied. • The polymers obtained possess a rigid structure, which affects their thermal properties. • The polymers are middle-permeable, however tend to exhibit "solubility controlled permeability". [ABSTRACT FROM AUTHOR]

Commercial metathesis polynorbornene is used for the fabrication of high-damping coatings and bulk materials that dissipate vibration and impact energies. Functionalization of this non-polar polymer can improve its adhesive, gas barrier, and other properties, thereby potentially expanding its application area. With this aim, the post-modification of polynorbornene was carried out by inserting ethylene–vinyl acetate–vinyl alcohol blocks into its backbone via the cross-metathesis of polynorbornene with poly(5-acetoxy-1-octenylene) and subsequent deacetylation and hydrogenation of the obtained multiblock copolymers. For the first time, epoxy groups were introduced into the main chains of these copolymers, followed by the oxirane ring opening reaction. The influence of post-modification on the thermal, gas separation, and mechanical properties of the new copolymers was studied. It was shown that the gas permeability of the copolymer significantly depends on its composition, as well as on the amounts of hydroxyl and epoxy groups. The developed methods efficiently improve the barrier properties, reducing the oxygen permeability by 15–33 times in comparison with polynorbornene. The obtained results are promising for various applications and can be extended to a broader family of polydienes and other polymers containing backbone double bonds. [ABSTRACT FROM AUTHOR]

High-temperature polymer-electrolyte membrane fuel cells (HT-PEMFCs) are a very important type of fuel cells since they operate at 150–200 °C, making it possible to use hydrogen contaminated with CO. However, the need to improve the stability and other properties of gas-diffusion electrodes still impedes their distribution. Self-supporting anodes based on carbon nanofibers (CNF) are prepared using the electrospinning method from a polyacrylonitrile solution containing zirconium salt, followed by pyrolysis. After the deposition of Pt nanoparticles on the CNF surface, the composite anodes are obtained. A new self-phosphorylating polybenzimidazole of the 6F family is applied to the Pt/CNF surface to improve the triple-phase boundary, gas transport, and proton conductivity of the anode. This polymer coating ensures a continuous interface between the anode and proton-conducting membrane. The polymer is investigated using CO2 adsorption, TGA, DTA, FTIR, GPC, and gas permeability measurements. The anodes are studied using SEM, HAADF STEM, and CV. The operation of the membrane–electrode assembly in the H2/air HT-PEMFC shows that the application of the new PBI of the 6F family with good gas permeability as a coating for the CNF anodes results in an enhancement of HT-PEMFC performance, reaching 500 mW/cm2 at 1.3 A/cm2 (at 180 °C), compared with the previously studied PBI-O-PhT-P polymer. [ABSTRACT FROM AUTHOR]

Poly(vinyl trimethylsilane) (PVTMS) films were subjected to direct surface fluorination in liquid medium (perfluorodecalin). The samples were investigated using several techniques: SEM-XEDS, XPS, ATR-IR, and contact angle measurement. The methods used allowed us to estimate chemical changes occurring because of the treatment. ATR-IR showed that most of the changes occurred in the Si(CH3)3 group. Monofluorinated Si(CH3)3 groups formed in the near-surface layer (Ge crystal, 0.66 µm penetration) after 30 min of fluorination, and then di- and trifluorinated groups appeared. Oxidation of the film with oxygen was also shown with the use of ZnSe crystal (2 µm penetration). The XPS method allowed an assessment of the ratio of the main elements at the surface of the fluorinated film. Two different exponential models were proposed to fit the experimental data of SEM-XEDS. Based on the model with the intercept, the depth of fluorination was estimated to be ≤1.1 µm, which is consistent with the result from the literature for the gas-phase fluorination. Contact angle measurements showed that oxidation of the PVTMS surface prevailed for the first 45 min of fluorination (surface hydrophilization) with a subsequent fluorine content increase and hydrophobization of the surface upon 60 min of fluorination. [ABSTRACT FROM AUTHOR]

Semi-ladder high-molecular polynaphthoylenebenzimidazoles (PNBI) were synthesized through polyaminonaphtoyleneimide (PANI) formation and thermal cyclization at 350 °C. The structures of PANIs and PNBIs were confirmed by NMR, GPC and FTIR. Polymer films were obtained from PANI pre-polymer by solution-cast technique. After thermal cyclization, the PNBI films exhibit excellent mechanical properties: tensile strength of 95–174 MPa, Young's modulus of 1.5–2.4 GPa and elongation at break of 10–50%. The PNBIs are located near the upper bound of the 1991 Robeson diagram for O 2 /N 2 , H 2 /N 2 and H 2 /CH 4 gas pairs, while the PNBI with a hexafluoroisopropylidene bridge (PNBI-4) overcomes it for CO 2 /CH 4 , approaching the upper bound of the 2008 Robeson diagram. A peculiarity of the synthesized polymers is lower gas diffusion coefficients and higher gas solubility coefficients, which are close to polypyrrolones and PIM family polymers. The higher PNBI diffusion selectivity identifies them as organic molecular sieves, as confirmed by the specific surface area of PNBI-4, which is close to PIM-1. The data obtained allows to classify the studied PNBIs as unexpected PIM relatives. The synthesized PNBIs are polymer molecular sieves and, unexpectedly, belong to the polymer of intrinsic microporosity family. [Display omitted] • The PNBI gas transport properties have been obtained. • The studied PNBIs lie on the upper bounds of the 1991 Robeson diagrams. • PNBI-4 is higher than the upper bound on the 1991 Robeson diagram for CO 2 /CH 4. • PNBI-4 is approaching the upper bound of the 2008 Robeson diagram for CO 2 /CH 4. • PNBI-4 possesses a microporous structure similar to the one of PIM-1. [ABSTRACT FROM AUTHOR]