The transformation and degradation of Nafion® solutions under ultrasonic treatment. The effect on transport and mechanical properties of the resultant membranes

Сафронова Е.; Pourcelly G.; A. B. Yaroslavtsev

doi:10.1016/j.polymdegradstab.2020.109229

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The transformation and degradation of Nafion® solutions under ultrasonic treatment. The effect on transport and mechanical properties of the resultant membranes

Polymer Degradation and Stability. 2020. Vol. 178. P. 109229.

Сафронова Е., Pourcelly G., Yaroslavtsev A. B.

This work addresses the study of the effect of ultrasonic (US) treatment on the properties of alcohol solutions of perfluorinated sulfonic acid polymer Nafion® and cast membranes. The effect of the duration of US treatment on the physico-chemical properties (water uptake, transport and mechanical properties) of the resulted membranes is described for the first time. Upon the US treatment, viscosity of the polymer solutions irreversibly decreases due to deagglomeration and rupture of macromolecular chains. As a result of the US treatment, mechanical properties of the Nafion® membranes are deteriorated. The dependences of water uptake and conductivity of the Nafion® membranes in the proton form on sonication time pass the maximum (at 30–45 min). Due to the sonication of polymer solutions, proton conductivity of the membranes increases by 40–45%. Upon extended sonication, the content of sulfonic acid groups decreases, and carboxyl groups are formed at the ends of macromolecules. Thus, water uptake of the membranes prepared from the polymer solutions after the US treatment for 60 min decreases, and conductivity of the obtained membranes in the H+-form is reduced. However, for the Nafion® membranes in the Na+-form, as the duration of the US treatment is extended, their conductivity and diffusion permeability tend to increase due to the enhanced connectivity of pores and channels as well as due to the participation of carboxyl groups in the ionic transport. Upon extended sonication, selectivity of the cation transfer through the membranes is reduced. The results of this work highlight the importance of the proper selection of favorable conditions of the US treatment of the solutions of perfluorinated sulfonic acid polymers for the preparation of hybrid membranes and for the development of catalytic layers of membrane-electrode assemblies for fuel cells.

Research target: Chemistry

Priority areas: engineering science

Language: English

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Keywords: degradation Nafion hybrid membranes Ultrasonic degradation Catalyst ink

MPI+OpenMP implementation of resolution-of-the-identity Hartree-Fock method exploiting permutational symmetry of three-center electron repulsion integrals

Kashpurovich I., Oleynichenko A., Stegailov V., Supercomputing Frontiers and Innovations 2026 Vol. 13 No. 1 P. 52–73

We report a high-performance implementation of the resolution-of-the-identity Hartree–Fock method that fully exploits the permutational symmetry of three-center electron repulsion integrals (ERI). The present implementation adopts a hybrid MPI+OpenMP parallelization strategy. Two different algorithmic approaches (with and without the pre-transformation of ERIs) are compared. A custom data layout introduced previously is employed. Designed to efficiently ...

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Gureev M., Advanced Science 2026 P. 1–13

Targeted protein degradation represents a promising therapeutic strategy, yet its broader application is often limited by the scarcity of usable E3 ligases. Glutathione peroxidase 4 (GPX4) is a key target for inducing ferroptosis, but achieving sustained and potent inhibition remains challenging with conventional enzymatic inhibitors. Herein, we report the first small‐molecule GPX4 degraders that incorporate ...

Added: September 26, 2026

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Budkov Y., Kiselev M. G., Journal of Chemical Physics 2026 Vol. 165 No. 12 Article 124508

We develop a three-mode statistical-mechanical theory for a two-conformer solute in a near-critical solvent. A compressible lattice model with vacancies yields the Gaussian free-energy functional for a critical conserved density, an orthogonal noncritical conserved mode, and the local conformer fraction. Their couplings follow from packing and cohesive interactions, rather than being introduced phenomenologically. Kawasaki transport of the two conserved fields and ...

Added: September 24, 2026

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Yurova P., Stenina I., Yaroslavtsev A. B., Membranes and Membrane Technologies 2026 Vol. 8 No. 1 P. 1–8

In this work, the effect of applying layers of polyethyleneimines with different molecular weights (1300 and 25000 Da), polystyrene sulfonic acid or sodium polyacrylate on the surface of the heterogeneous membrane MK-40 on the selectivity to singly charged ions was investigated. It is shown that the modification leads to an increase in the selectivity coefficients P(Na+/Ca2+) and P(Li+/Mg2+), ...

Added: September 24, 2026

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Корзникова Е. А., Mukhametov A., Samikov I. et al., Computational Condensed Matter 2026 Vol. 47 Article e01295

Aluminium (Al)- and copper (Cu)-based alloys may corrode in harsh environments. This occurs because corrosion ions penetrate into the intergranular structures and react with the atoms of the host matrix at the grain boundaries (GBs). Therefore, elucidating atomic-level mechanisms at GBs is critical for enhancing Al/Cu corrosion resistance upon penetration of corrosion ions, such as ...

Added: September 24, 2026

Exact screening constraints for theories of inhomogeneous electrolytes: Generalized Stillinger–Lovett relations and a nonlinear Ward hierarchy

Budkov Y., Journal of Chemical Physics 2026 Vol. 165 No. 12 Article 124105

Exact theories of electrolyte structure must satisfy the nonlocal constraints imposed by electrostatic screening, yet these constraints are most commonly formulated only for homogeneous bulk systems and at the level of two-point correlations. Here, we develop a unified field-theoretic framework that extends them to general inhomogeneous ionic fluids and nonlinear charge correlations. Using a standard ...

Added: September 22, 2026

Formation of Singly Bonded {CpCo(CO)-η 2 -C 60 – } 2 Dimers upon the Dimerization of the CpCo(CO)-η 2 -C 60 •– Radical Anions

sobov P., Yakushev I., Shestakov A. et al., Organometallics 2025 Vol. 44 No. 24 P. 2873–2881

Interaction of {Cryptand(K+)}(C60•–) with CpCo(CO)2 yields the air-sensitive crystalline salt {Cryptand(K+)}{CpCo(CO)-η2-C60•–} (1), in which C60•– replaces carbonyl group in CpCo(CO)2. Two Co–C bonds of 2.028(9) and 2.057(8)Å are formed. The magnetic moment of 1 is 1.72 μB, indicating a doublet S = 1/2 spin state of {CpCo(CO)-η2-C60•–} at 300 K. The compound shows a broad ...

Added: September 20, 2026

Substituent-driven supramolecular assembly in Hg(II) bromide complexes with pyridine-based hydrazone ligands: crystal structures, Hirshfeld surface analysis, and DFT/QTAIM study

Novikov A., Polyhedron 2026 Vol. 299 Article 118383

Three new Hg(II) bromide complexes, HgBr2L (1–3) (L1 = N′-(pyridin-2-ylmethylene)isonicotinohydrazide, L2 = N′-(1-(pyridin-2-yl)ethylidene)isonicotinohydrazide, L3 = N′-(phenyl(pyridin-2-yl)methylene)isonicotinohydrazide), have been synthesized in good yields and thoroughly characterized. Single-crystal X-ray diffraction analyses unveil that complexes 1 and 3 are mononuclear, while complex 2 is dinuclear. All complexes further assemble into one-dimensional supramolecular chains mediated by N–H···N hydrogen bonds, which are reinforced by π···π stacking and Br···Br halogen interactions. Systematic variation ...

Added: September 16, 2026

Water confined in heterogeneous clay–quartz pores: Structure and dynamics from atomistic simulations

Glushak A., Tararushkin E., Smirnov G., Colloids and Surfaces A: Physicochemical and Engineering Aspects 2027 Vol. 752 Article 141756

The molecular-scale behavior of water in heterogeneous clay–quartz systems is critical for understanding cementation processes in natural soils and compacted bentonite, which is crucial for oil recovery and nuclear waste disposal barriers construction. Here we investigate how heterogeneity of mixed Na-montmorillonite and α-quartz surfaces affect water structure and dynamics in nanopores of 2.5 to 60 Å ...

Added: September 15, 2026

Coordination-driven assemblies of thioindigo and phthalocyanine chromophores: tuning optical absorption and magnetic interactions

Kolin N., Nazarov D., Krivenko K. et al., Dyes and Pigments 2026 Vol. 254 Article 113957

Interaction of thioindigo dianions with metal phthalocyanines, MPc, where M = MgII, MnII, AlIIICl and SiIVCl2, in the presence of cryptand[2.2.2] produces anionic and neutral complexes: {Crypt(K+)}2{(trans-thioindigo2−)⋅(MgIIPc)2}2−⋅2C6H4Cl2 (1); {Crypt(Cs+)}2{(trans-thioindigo2−)⋅(MnIIPc)2}2− (2), {Crypt(K+)}{(cis-Hthioindigo−)2⋅(AlIIIPc)}− (3) and {(cis-Hthioindigo−)2⋅(SiIVPc)} (4). Bidentate thioindigo2− ligand forms symmetric binuclear dimers in 1 and 2 with short M-O(thioindigo2−) bonds of 1.899(2) and 1.984(6) Å length for ...

Added: September 14, 2026

Doubly Reduced Phthalocyanine Complexes of V(IV), Cu(II), and Sn(II): Synthesis, Structure, and Spin Dynamics

Faraonov M., Romanenko N., Ivanov T. et al., Dalton Transactions 2026 Vol. 55 No. 24 P. 9428–9438

Doubly reduced phthalocyanine complexes remain largely unexplored despite their potential relevance for molecular spin-based applications. Herein, we report the synthesis of a series of crystalline complexes, {cryptand(Cs + )} 2 [M(Pc) 4– ] 2–. ...

Added: September 14, 2026

Binuclear and trinuclear 3d-metal complexes of HATNA and HAT(CN)6 with unique magnetic behavior: from extremely strong antiferromagnetic coupling to opposite sign of zero-field splitting in the same complex

Mikhailenko M., Astakhova T., Timokhina E. N. et al., Inorganic Chemistry Frontiers 2026 Vol. 13 No. 14 P. 6145–6156

series of anionic bi- and trinuclear complexes of Co II , Fe II , and Mn II with hexaazatrinaphthylene (HATNA) and hexaazatriphenylenehexacarbonitrile (HAT(CN) 6 ), incorporating paramagnetic Cp* 2 Fe + cations ( S = 1/2), were obtained and investigated. ...

Added: September 14, 2026

1D and 2D coordination polymers based on ring-reduced freebase and copper-containing meso-tetra(4-pyridyl)porphyrins and M(III) (TMHD) 3 units (M = Dy, Tb and Gd; TMHD: 2,2,6,6-tetramethyl-3,5-heptanedionate)

Nazarov D., Yakushev I. A., Kuzmin A. V. et al., Inorganic Chemistry Frontiers 2026 Vol. 13 No. 11 P. 5039–5050

Reduced tetra(4-pyridyl)porphyrins (H 2 TPyP and Cu II TPyP) form polymers with M III (TMHD) 3 (M = Dy, Tb and Gd). Folded zigzag 2D and linear 1D polymers are obtained. Their structure, optical and magnetic properties are investigated. ...

Added: September 14, 2026

Singlet–Triplet Transitions in the Dianionic Complex of Fullerene C 60 with Iron Carbonyl: (TBA + ) 2 {[Fe 2 (CO) 6 ]-η 2 ,η 2 -C 60 } 2–

Sobov P. A., Yakushev I. A., Shestakov A. et al., Inorganic Chemistry 2026 Vol. 65 No. 16 P. 9107–9115

Interaction of fullerene C60 with Cs2Fe(CO)4 in the presence of two equivalents of tetrabutylammonium iodide (TBAI) yields the first dianionic coordination complex of fullerene: (TBA+)2{[Fe2(CO)6]-η2,η2-C60}2– (1). According to magnetic data and DFT calculations, complex 1 has a diamagnetic ground (S = 0) and a triplet excited state (S = 1) populated above 80 K. As ...

Added: September 14, 2026

Crystalline Trinuclear Exo- and Endocyclic Complexes of a Tetrapyrazinoporphyrazine Ligand with 3 d - and 4 f -Metals

Faraonov M., Romanenko N., Ivanov T. et al., Crystal Growth & Design 2026 Vol. 26 No. 7 P. 2792–2801

A redox-active tetrapyrazinoporphyrazine ligand was used as a platform for the design of multimetallic coordination complexes. The first paramagnetic homo- and heterotrimetallic complexes have been obtained as crystals through the reaction of iron(II) octaethyltetrapyrazinoporphyrazine, FeII(Et8TPyzPz), with 3d- (FeII, CoII) and 4f-metal (DyIII) iodides. In these conditions, tetrapyrazinoporphyrazine can coordinate to metals to form exo- and ...

Added: September 14, 2026

Complex of fullerene C60 with partial charge transfer: {(dppf)CpFe(CO)}+(C60)-⋅C6H4Cl2 (δ = 0.54–0.86), where dppf is bis(diphenylphosphino)ferrocene ligand

Sobov P. A., Khasanov S., Kuzmin A. V. et al., Inorganic Chemistry Communications 2026 Vol. 185 Article 116055

New complex {(dppf)CpFe(CO)}(C60)⋅C6H4Cl2 (1) was obtained when stoichiometric mixture of C60 and CoII(dppf)Cl2 is reduced by two equivalents of (Cs+){CpFe(CO)2−} (dppf: 1,1`-bis(diphenylphosphino)ferrocene). CpFe(CO)2− anion reduces CoII(dppf)Cl2 and CpFe(CO)2 abstracts the dppf ligand from Co(dppf) forming (dppf)CpFeI(CO). Electron transfer from (dppf)CpFeI(CO) to C60 is observed. As a result, the state of {(dppf)CpFe(CO)}δ+(C60)δ−⋅C6H4Cl2 (δ = 0.54–0.86) is intermediate between ...

Added: September 14, 2026

Mono- and binuclear complexes of iron(II) and cobalt(II) with deprotonated trans-indigo anions. Effect of cationic surrounding on structure and magnetic properties.

Krivenko K., Kuzmin A. V., Mikhailenko M. et al., Dyes and Pigments 2026 Vol. 246 Article 113342

Mono- and binuclear complexes of FeII and CoII with deprotonated trans-indigo were obtained. Reduction of indigo by metallic iron in the presence of crystal violet (CV) yields (CV+)[(FeCl2)HIndigo]−⋅C6H4Cl2 (1). The reaction of FeI2 and CoI2 with one equivalent of decamethylchromocene (Cp∗2Cr) and one or half equivalent of indigo yields mononuclear (Cp∗2Cr+)[(CoI2)HIndigo]−⋅C6H4Cl2 (2), (Cp∗2Cr+)[(FeI2)HIndigo]−⋅ xC6H4Cl2, where ...

Added: September 14, 2026

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Sosunov E., Skabitsky I. V., Churakov A. et al., Crystal Growth & Design 2026 Vol. 26 No. 4 P. 1775–1782

Polynuclear 5d–3d assemblies represent a promising class of systems for exploring the interplay among electronic structure, magnetism, and self-assembly. Here, we report the synthesis and structural characterization of the first heterometallic wheel-shaped Pt–Mn cluster, [PtIV12PtII6Mn18(OAc)72(μ3-O)12]·43C6H6(1), which incorporates 36 metal centers. The giant ring is constructed from alternating PtIIMnII paddlewheel fragments and PtIV2Mn2 oxo-acetate units, bridged ...

Added: September 14, 2026

Effect of the size of the substituents in triptycene (TPC-X) on the magnetic and conducting properties of the layered 2D organic metals (MDABCO+)(C60•−)·(TPC-X), where X = H, Br, and I

Sobov P. A., Kuzmin A. V., Shevchun A. F. et al., Synthetic Metals 2025 Vol. 313 Article 117904

Modification of the neutral triptycene TPC-X molecule by increasing the size of the X substituent at the 9th position from X = H to Br and I affects the magnetic and conducting properties of the (MDABCO+)(C60•−)(TPC-X) salts (1–3, respectively), where MDABCO+ is N-methyldiazabicyclooctanium. These salts feature hexagonal fullerene layers composed of C60•−, which remain undimerized owing to ...

Added: September 14, 2026

Salts of Tetraselenatetracene and Bis(ethylenedithio)tetrathiafulvalene with Metal Hexafluoroacetylacetonate Anions: MnII(hfac)3–, CoII(hfac)2Cl–, and PrIII(hfac)4–

Flakina A. M., Nazarov D., Faraonov M. et al., Crystal Growth & Design 2025 Vol. 25 No. 15 P. 6332–6344

Oxidation of tetraselenatetracene (TSeT) and bis(ethylenedithio)tetrathiafulvalene (BEDT-TTF) by p-chloranil in the presence of metal hexafluoroacetylacetonates: MnII(hfac)2, CoII(hfac)2 and PrIII(hfac)3 followed by precipitation of crystals by n-hexane produces (TSeT1.5)+{MnII(hfac)3–} (1), (TSeT1.5)+{PrIII(hfac)4–} (3), (TSeT2)+{CoII(hfac)2Cl–} (4), and (ET3)+{MnII(hfac)3–} (5). Thioindigo dye is introduced into (TSeT1.5)+ (Thioindigo1.5){MnII(hfac)3–} (2) due to the appearance of specific C═O···(Se–Se bond) interactions accompanied by ...

Added: September 14, 2026

Complex of copper(II) hexafluoroacetylacetonate with photochromic spiropyran in the merocyanine form: Field-induced slow magnetic relaxation and quantum coherence for Cu(II) (S = 1/2) and photoswitching of spiropyran ligand

Osipov N., Faraonov M., Yakushev I. A. et al., Dalton Transactions 2025 Vol. 54 No. 32 P. 12180–12188

The interaction of photochromic 8-methoxy-1′,3′,3′-trimethyl-6-nitro-spiro[chromene-2,2′-indole] (MNSP) spiropyran with copper(II) hexafluoroacetylacetonate yields a deep red–violet solution due to a coordination-induced transition of MNSP from its closed form to the colored, open merocyanine (MC) form. The crystal structure of {CuII(hfac)2·MNSP} (1) shows coordination of two oxygen atoms in MNSP to CuII, forming a distorted octahedral geometry with ...

Added: September 14, 2026

Complexes of d‐ and f‐metal Ions with Redox‐Active and Highly Symmetric Truxenone Ligand: Effect of Cations and Coordination on Distortions of Radical Anions and Singlet–Triplet Transition in Dianions

Krivenko K., Shestakov A., Faraonov M. et al., European Journal of Inorganic Chemistry 2025 Vol. 28 No. 14 Article e202400760

Truxenone (Tr) with high C3h symmetry forms crystalline radical anion and dianion salts. The {Bu3MeP+}(Tr⋅−) (1) and {Cp*2Co+)}(Tr⋅−)⋅2 C6H4Cl2 (2) show intense low‐energy absorption up to 2000 nm. Calculations predict Jahn–Teller distortions for Tr⋅−, which are enhanced by the asymmetric approach of cations to Tr⋅−, leading to C=O bond length alternation and EPR signal asymmetry in 2. ...

Added: September 14, 2026

Complexes (TBA+){(TMI-NPS)2·LnIIII4}− (Ln = Dy, Tb) with two axial photochromic spiropyran ligands: photoswitching and zero-field SIM behaviour with a high magnetization blocking barrier for the Dy complex

Osipov N., Faraonov M., Kuzmin A. V. et al., Inorganic Chemistry Frontiers 2025 Vol. 12 No. 5 P. 2092–2102

Two photochromic spiropyran molecules (1,3,3-trimethylindolino-β-naphthopyrylospiran, TMI-NPS) react in the open form with LnIII iodides (Ln = Dy, Tb) to form in the presence of TBAI crystalline (TBA+){(TMI-NPS)2·LnIIII4}−·0.5C6H4Cl2 (1 and 2, respectively). Two TMI-NPS ligands are coordinated to lanthanides (Ln) by oxygen atoms at the axial position, and four iodide anions located at the equatorial position ...

Added: September 14, 2026

Surface-sulfonated Al₂O₃, CeO₂, and TiO₂ as functional fillers for Nafion-type gel polymer electrolytes for lithium metal batteries

Voropaeva D., S. Novikova, I. Stenina et al., Solid State Ionics 2026 Vol. 445 Article 117288

Composite gel polymer electrolytes based on a perfluorinated sulfonic acid cation-exchange MF-4SC membrane containing surface-sulfonated nanoparticles of aluminum oxide, cerium (IV) oxide, and titanium oxide (sAl2O3, sCeO2, and sTiO2, respectively) were prepared by casting from a dispersion in N,N-dimethylformamide and plasticized with a 1,3-dioxolane/1,2-dimethoxyethane mixture. The influence of the filler nature on ionic conductivity, solvent uptake, activation energy, lithium ...

Added: July 30, 2026