Bakirov, Artem Vadimovich

Liubimovskii S.O., Novikov V.S., Anokhin E.V., Kuznetsov S.M., Bakirov A.V., Demina V.A., Sedush N.G., Chvalun S.N., Moskovskiy M.N., Gudkov S.V., Yu. Nikolaeva G.

Ardabevskaia S.N., Chamkina E.S., Krasnova I.Y., Milenin S.A., Khanin D.A., Demchenko N.V., Bakirov A.V., Serenko O.A., Shifrina Z.B., Chvalun S.N., Muzafarov A.M.

ABSTRACTThe synthesis of hybrid dendrimers composed of 1st, 2nd, and 3rd generation branched carbosilane macromolecules as the core, linked to a polyphenylene shell through a long hydrocarbon (C11) spacer, is described. This approach, employing a sequence of hydrosilylation and click reactions, starts with the preparation of 1‐(11‐azidoundecyl)‐1,1,3,3‐tetramethyldisiloxane followed by its reaction with allyl‐functionalized carbosilane dendrimers, culminating in a CuAAC reaction with monoethynylhexaphenylbenzene. Structural analysis using SAXS and WAXS revealed the significant influence of the long alkyl spacers on crystal lattice formation, driven by the ordered motifs arising from the hexaphenylbenzene terminal units.

Любимовский С.О., Новиков В.С., Васимов Д.Д., Кузнецов С.М., Анохин Е.В., Бакиров А.В., Калинин К.Т., Демина В.А., Седуш Н.Г., Чвалун С.Н., Московский М.Н., Николаева Г.Ю.

В работе проводится исследование спектров комбинационного рассеяния (КР) света ряда материалов на основе полилактида: стереоизомеров полилактида, олигомеров L-лактида, сополимеров L-лактида и ε-капролактона, композитов поли(L-лактида) и гидроксиапатита. Установлено, что по спектрам КР можно определять состав и степень кристалличности широкого круга материалов на основе полилактида. Развитие такой методики очень важно для разработки инновационных материалов на основе полилактида, используемых как для разнообразных медицинских применений, так и, например, при создании биоразлагаемой одноразовой упаковки для решения проблем загрязнения окружающей среды.

Meshkov I.B., Mazhorova N.G., Bakirov A.V., Vasil’ev S.G., Kalinina A.A., Bystrova A.V., Muzafarov A.M.

Silica fillers have been a cornerstone in chemical technology due to their versatility, availability, and ease of integration into various formulations. Recent advancements, including chlorine-free synthesis of alkoxysilanes, have paved the way for alternative materials like polymethylsilsesquioxane (PMSSO). This study explores the structural evolution and properties of a hydrophobic PMSSO xerogel, synthesized through hydrolytic polycondensation of methyltriethoxysilane (MTEOS). PMSSO exhibits exceptional hydrophobicity, high specific surface area, and compatibility with polymer matrices, making it a promising filler for applications in rubber products, lubricants, and cosmetics. We developed a straightforward synthesis method for producing PMSSO xerogel that avoids toxic solvents and organochlorosilanes, ensuring safety and sustainability. The reaction conditions, particularly the amount of alkali and neutralization parameters, were found to significantly influence the properties of the final xerogels, such as specific surface area. Optimization of the synthesis parameters allow for obtaining PMSSO xerogels with a specific surface area about 600 m2/g. These findings underscore PMSSO’s potential as a versatile, eco-friendly alternative to conventional silica fillers, offering tailored properties for diverse industrial applications.

Mensharapov R.M., Spasov D.D., Sinyakov M.V., Grineva D.E., Nagorny S.V., Chumakov R.G., Bakirov A.V., Ivanova N.A.

The activities of Pt electrocatalysts modified with a prepared silica powder (with SiO2 contents of 3 and 7 wt%) in the oxygen reduction reaction in the temperature range from 0 °C to 50 °C were investigated by the rotating disk electrode technique to evaluate their efficiency in the process of the cold start of a proton-exchange membrane fuel cell (PEMFC). An increase in the mass activity of the Pt-SiO2/C electrocatalyst in comparison with Pt/C was observed, which can be attributed to a more dispersed distribution of platinum particles on the support surface and a decrease in their size. The activity values of the silica-modified electrocatalysts in the oxygen reduction reaction were approximately two-fold higher at 1 °C and four-fold higher at elevated temperatures of up to 50 °C in comparison with Pt/C, which makes their application in PEMFCs at low temperatures, including in the process of cold start, a promising avenue for further investigation.

Kuznetsova E.V., Vantsyan M.A., Kalinin K.T., Konshina E.A., Sedush N.G., Bakirov A.V., Streltsov D.R., Bukreeva T.V., Chvalun S.N.

The layer-by-layer adsorption of polyethyleneimine and dextran sulfate onto the nanoparticles of biodegradable poly(D,L-lactide-co-glycolide) was conducted to produce potential delivery system of cyanocobalamin. The modified poly(D,L-lactide-co-glycolide) particles are found to be colloidal stable, nanosized with the value of hydrodynamic diameter of 210 nm and polydispersity index of 0.22. It was established that the content of cyanocobalamin absorbed by polyelectrolyte shell of the modified particles was 16 wt.%. It was observed that the cyanocobalamin loading slightly affects the physicochemical parameters of the particles. Moreover, the obtained nanosomal form of the cyanocobalamin does not require to be lyophilized; it could be stored as a dispersion due to extremely slow release of loaded active agent under normal ambient conditions at 25 °C. A comprehensive study of the poly(D,L-lactide-co-glycolide) nanoparticles modified by oppositely charged polyelectrolytes loaded with the cyanocobalamin using dynamic light scattering, analytical ultracentrifugation, small-angle X-ray scattering and atomic force microscopy allows to evaluate the value of thickness of the polyelectrolyte shell onto the poly(D,L-lactide-co-glycolide) core, which is found to be about 30 nm. The developed nanocarriers based on the poly(D,L-lactide-co-glycolide) particles modified by the alternating adsorption of polyethyleneimine and dextran sulfate can be considered as a promising candidate for simultaneous delivery of both hydrophobic agents loaded into the poly(D,L-lactide-co-glycolide) core and water-soluble cyanocobalamin incorporated into the polyelectrolyte shell.

Mensharapov R.M., Ivanova N.A., Spasov D.D., Bakirov A.V., Fateev V.N.

Kuznetsov N.M., Zakharevich A.A., Vdovichenko A.Y., Kovaleva V.V., Zagoskin Y.D., Bakirov A.V., Malakhov S.N., Grigoriev T.E., Chvalun S.N.

AbstractA chemical modification of cellulose diacetate by phthalate and nitrate was performed to increase solubility in organic solvents and change the electrical properties. The role of substituents on the conductivity, permittivity, and polarizability of cellulose films is revealed. It has been shown that highly porous micro particles can be obtained from cellulose derivatives by a simple and technological freeze‐drying method. The resulting micro sized aerogels have a predominantly spherical morphology and amorphous structure. Suspensions of porous particles of nitro‐ and phthalylated cellulose derivatives in silicone oil have an increased dielectric permittivity compared to cellulose diacetate particles. Produced particles are novel promising material with tunable electrical properties for advanced applications in composites, including for electrorheological fluids.

Bakanov K.K., Ardabevskaia S.N., Bezlepkina K.A., Klokova K.S., Krupnin A.E., Buzin A.I., Khanin D.A., Kostrov S.A., Bakirov A.V., Drozdov F.V., Chvalun S.N., Muzafarov A.M., Zou J., Kramarenko E.Y., Milenin S.A.

Polydimethylsiloxanes with improved mechanical properties that can be processed by 3D printing are in high demand for scientific and practical applications. In our article, we proposed the synthesis of new PDMS copolymers with urethane and triazole fragments using the CuAAC reaction mechanism, as well as 3D printing with the obtained copolymers. Two types of copolymers, with molecular weights of 3000 and 6000 Da of PDMS block length, were prepared and characterized by GPC, IR spectroscopy, TGA, DSC, TMA, SAXS, and rheological measurements to determine their physicochemical properties. The synthesized copolymers were found to be suitable for processing by extrusion 3D printing. This demonstrated the ability to 3D print macroscale models of varying shapes and complexity. The resulting materials retained their printed shape over time.

Yarysheva A.Y., Kopnov A.Y., Berkovich A.K., Bakirov A.V., Yarysheva L.M., Arzhakova O.V., Chvalun S.N.

Dyadishchev I.V., Balakirev D.O., Kalinichenko N.K., Svidchenko E.A., Surin N.M., Peregudova S.M., Vasilev V.G., Shashkanova O.Y., Bakirov A.V., Ponomarenko S.A., Luponosov Y.N.

Liquid organic luminophores (LOLs) have been actively investigated as a new generation of functional materials in various fields of organic optoelectronics and photonics. However, many issues, including the structure–properties relationships and the development of LOLs emitting light in the red spectral range, remain poorly investigated. Here we report on the synthesis and investigation of a series of novel conjugated luminescent molecules consisting of a central 2,1,3-benzothiadiazole electron-withdrawing unit and lateral thiophene or phenylene electron-donating fragments with terminal trialkylsilyl units as solubilizing groups (SGs). Thermal and thermo-oxidative stability, phase behavior, rheology, and optical and electrochemical properties of the obtained luminophores were studied and compared to their counterparts without SGs or with ineffective SGs for liquefaction. The target compounds are luminescent liquids with low glass transition temperatures (up to −65 °C) and viscosities (up to 1.7 Pa·s) or liquid crystal materials emitting light in almost the entire visible spectral range with high photoluminescence quantum yield (PLQY) both in solutions (up to 97 %) and films (up to 87 %). For the first time, the application of LOLs as a new generation of organic liquid scintillators was demonstrated, achieving a light yield up to 1.7 times higher than that of a standard liquid scintillator.

Liubimovskii S.O., Novikov V.S., Vasimov D.D., Kuznetsov S.M., Sagitova E.A., Dmitryakov P.V., Bakirov A.V., Sedush N.G., Chvalun S.N., Moskovskiy M.N., Nikolaeva G.Y.

We carried out a Raman study of a series of poly(L-lactide) (PLLA) samples annealed for different periods of time and therefore having different crystallinity degree. We compared the results with our recent study of the series of poly(L-lactide-co-ε-caprolactone) (PLCL) copolymers with the ε-caprolactone (CL) content ranging from 5 to 30 mol %. X-ray diffraction (XRD) analysis showed that the crystallinity degree of the analyzed PLLA-based materials is in the range of 0–86%. We suggest using the ratio of the peak intensities of the PLLA Raman bands at 411 and 874 cm–1 to evaluate the crystallinity degree of PLLA homopolymers as well as PLLA blocks in the PLCL copolymers. This ratio does not depend on the CL content in the copolymers, it strongly depends on the crystallinity degree of PLLA (PLLA blocks in the PLCL copolymers) and it is a linear function of the crystallinity degree, measured by XRD analysis. We carried out quantum chemical calculations of the optimized geometries and Raman spectra of PLLA oligomers in the conformation of helix 103 with the number of monomeric units from 5 to 12. The results of the calculations revealed that the ratio of the intensities of the bands at 411 and 874 cm–1 weakly depends on the oligomer length for the number of the PLLA monomeric units more than 7.

Liubimovskii S.O., Novikov V.S., Sagitova E.A., Kuznetsov S.M., Bakirov A.V., Dmitryakov P.V., Sedush N.G., Chvalun S.N., Ustynyuk L.Y., Kuzmin V.V., Vasimov D.D., Moskovskiy M.N., Nikolaeva G.Y.

In this work, we study two series of the copolymers of L-lactide (LLA) and ε-caprolactone (CL) with the CL molar content of 5, 15, and 30 %. The first series was the commercial semicrystalline granules (Corbion, Netherlands), which we analyzed without any additional modification. The second series was amorphous films, prepared from the granules by hot pressing with the subsequent fast quenching in order to avoid the crystallization. We used Raman spectroscopy in conjunction with the quantum chemical modeling to evaluate the structure of the copolymers. As additional methods, we applied X-ray diffraction (XRD) analysis and differential scanning calorimetry (DSC). The main result of our study is the elaboration of the Raman methods of quantitative analysis of the relative contents of the comonomers and the crystallinity degree of the poly(L-lactide-co-ε-caprolactone). These methods are based on measurements of the ratios of the peak intensities of the poly(L-lactide) (PLLA) bands at 411 and 874 cm−1, the PLLA band at 2947 cm−1 and poly(ε-caprolactone) band at 2914 cm−1. Raman study showed that growth of the CL content causes the monotonous decrease in the crystallinity degree of PLLA blocks. Density functional theory analysis of LLA decamer in the conformation of helix 103 allows us to assign the PLLA Raman bands. The Raman data on the composition and crystallinity degree of the copolymers correlate very well with the results of XRD and DSC studies as well as with the information on the composition of the copolymers, provided by manufacturer.

Kovaleva V.V., Kuznetsov N.M., Zagoskin Y.D., Malakhov S.N., Bakirov A.V., Chvalun S.N.

A comprehensive study of the cellulose particle shape effect on electrorheological activity of their suspensions in polydimethylsiloxane was performed. Microparticles, nanorods and porous composite particles of cellulose with polyethylene glycol were considered as a filler. The structure of particles was established by a set of complementary methods, such as electron microscopy, infrared spectroscopy, and wide-angle X-ray scattering. The rheological behavior of suspensions filled by various types of particles changes under an electric field. The yield stress increases with electric field strength. The role of particle shape on the electrorheological properties of suspensions was revealed. The values of the yield stress of suspensions increase from microparticles to nanorods and porous composite particles at the same concentration and electric field strength. Porous composite particles of cellulose, a novel filler obtained by freeze-drying, demonstrates an enhanced electrorheological response compared to micro- and nanoparticles. The yield stress reaches 450 Pa at 7 kV/mm at an extremely low concentration of 1.0 wt%. Moreover, the porosity of the particles significantly increases the sedimentation stability of cellulose suspensions in polydimethylsiloxane. The high porosity of the filler makes it possible to obtain highly efficient electrorheological fluids at a sufficiently low concentration of the dispersed phase.

Bakirov A.V., Shcherbina M.A., Milenin S.A., Tatarinova E.A., Buzin A.I., Muzafarov A.M., Chvalun S.N.

Liubimovskii S.O., Novikov V.S., Anokhin E.V., Kuznetsov S.M., Bakirov A.V., Demina V.A., Sedush N.G., Chvalun S.N., Moskovskiy M.N., Gudkov S.V., Yu. Nikolaeva G.

Yu Y., Zheng W., Li B., Zhang C., Ming P.

Migulin D., Bezlepkina K., Buzin M., Bakirov A.

Ajayan J., Sreejith S., Ravindran A., George A., Mounika B.

Dabur D., Sharma N., Rana P., Wu H.

Tyubaeva P.M., Varyan I.A., Gasparyan K.G., Romanov R.R., Pozdnyakov A.S., Morokov E.S., Kolesnikov E.A., Podmasterev V.V., Popov A.A.

Zhu Z., Zou J., Ding Z., Wang M., Sun E., Zhang K., Zhao W., Wu M., Wang H.

Taouali W., Azazi A., Hassani R., EL-Araby E.H., Alimi K.

Vázquez-Aldana M., Sixto-Berrocal A.M., Arcos-Casarrubias J.A., Trujillo M.A., Cruz-Díaz M.R.

Li C., Ma L., Zhu Z., Li L., He C.

Munteanu L., Munteanu A., Sedlacik M.

Guo L., Song J., Deng J., Qiao J., Zhang J., Li C., Yuan S., Han B., Jee M.H., Ge Z., Zhang C., Lu G., Hao X., Woo H.Y., Sun Y.

AbstractA volatile solid additive strategy, which can effectively optimize the morphology of the photoactive layer with an ideal domain size and purity, has emerged as a promising approach to improve the photovoltaic performance of organic solar cells (OSCs). However, the precise role of solid additives in modulating charge and exciton dynamics, especially the recombination process, remains not fully understand. In this study, a solid additive, 1,4‐diiodo‐2,5‐dimethoxybenzene (DIDOB), is developed to improve the photovoltaic performance of OSCs and conduct a comprehensive investigation into its effect on the charge recombination process. As a result, the PM6:L8‐BO‐X‐based binary OSC processed with DIDOB achieves an excellent efficiency of 19.75% with a remarkable fill factor of 81.9%, owing to the optimal fiber network morphology, tighter and ordered molecular packing, as well as the suppression of both bimolecular and geminate recombination. Notably, the DIDOB exhibits broad universality as an additive in other non‐fullerene acceptor‐based OSCs. Impressively, the D18:PM6:L8‐BO‐based ternary device processed with DIDOB yielded an excellent efficiency of 20.11% (certified as 20.03%). This work highlights the effect of the solid additive on the charge recombination process within active layer and provides insights for the further development of OSCs.

Cotoarbă Y., Todor-Boer O., Botiz I.

Yin X., Chen F., Xiao L., Xu M., Li A., Li H.

Abstract Teleoperated robotic systems are widely used in daily life, but the actuators in their force feedback devices suffer from large structure volume, poor stability, low feedback torque, and slow response speeds. Based on the magnetorheological (MR) effect, a double-coil and double-disk MR damper structure is proposed in this paper. According to the constitutive model of MR fluid, the torque mathematical model of double coil and double disk MR Damper is established. Based on the orthogonal experiment method, the material, and geometry of the magnetic circuit are selected through the dynamic response range analysis and sensitivity analysis, and the magnetic circuit is designed by the equivalent reluctance method. Through the simulation of the steady magnetic field of the MR damper, the rationality of its structural design is verified. A prototype of the MR damper was built, and its performance was verified through experiments. The results show that the damper has a torque adjustment range from 20N•mm to 780N•mm, output torque fluctuation of 3.33%, and response time of 50ms. It means that the damper has the characteristics of wide torque adjustment range, compact structure, stable output, and fast response speed. Therefore, the damper has significant application potential in force feedback device.

Damonte G., Vallin A., Giribaldi L., Pellis A., Hakkarainen M., Subramaniyan S., Campaner P., Monticelli O.

Liubimovskii S.O., Ustynyuk L.Y., Novikov V.S., Kalinin K.T., Sedush N.G., Chvalun S.N., Gudkov S.V., Moskovskiy M.N., Nikolaeva G.Y.

Sixteen approximations of the density functional theory for calculating the structure and Raman spectra of the most stable α-phase of poly(L-lactide) (PLLA) with an orthorhombic crystalline lattice have been analyzed. It is shown that the GGA functionals OLYP and PBE provide good correspondence with experimental X-ray diffraction and Raman spectroscopy data. It is found that, when using extended basis sets of three- and four-exponential types, the choice of the functional affects the calculation results much more radically than the choice of the basis set.

Mensharapov R.M., Ivanova N.A., Spasov D.D., Bakirov A.V., Fateev V.N.

Maiorova L.A., Gromova O.A., Torshin I.Y., Bukreeva T.V., Pallaeva T.N., Nabatov B.V., Dereven’kov I.A., Bobrov Y.A., Bykov A.A., Demidov V.I., Kalacheva A.G., Bogacheva T.E., Grishina T.R., Nikolskaya E.D., Yabbarov N.G.

Recently, we have described the first supermolecular nanoentities of vitamin B

Kuznetsova E. ., Tyurnina A. ., Konshina E. ., Atamanova A. ., Kalinin K. ., Aleshin S. ., Shuvatova V. ., Posypanova G. ., Chvalun S. .

Effect of a poly(vinyl alcohol) (PVA) stabilizer concentration on the parameters of nanoparticles prepared by nanoprecipitation of biodegradable poly(D,L-lactide-co-glycolide) (PLGA) copolymers has been studied. It has been revealed that, at a constant concentration of the organic phase (5 mg/mL), the hydrodynamic diameter of PLGA particles does not depend on stabilizer concentration in an aqueous phase (2.5–15 mg/mL) and is ~130–140 nm, while the polydispersity index and the absolute value of the electrokinetic potential of the particles decrease with an increase in the PVA concentration. It has been shown that the PVA concentration has almost no effect on the content of a hydrophobic model drug, docetaxel, loaded into the PLGA particles, as well as on its in vitro cytotoxic activity against mice colorectal carcinoma cells and human embryo lung fibroblasts of the CT26 and WI-38 lines, respectively. At the same time, the ability of drug-loaded PLGA particles to lyophilization and subsequent redispersion in water depend on the stabilizer concentration: the higher the PVA concentration in the system the easier the redispersion of the particles to their initial sizes.

Zhang B., Ma P., Wang R., Cao H., Bao J.

AbstractDesigning efficient and durable electrocatalysts for oxygen reduction reaction (ORR) is essential for proton exchange membrane fuel cells (PEMFCs). Platinum‐based catalysts are considered efficient ORR catalysts due to their high activity. However, the degradation of Pt species leads to poor durability of catalysts, limiting their applications in PEMFCs. Herein, a Janus heterostructure is designed for high durability ORR in acidic media. The Janus heterostructure composes of crystalline platinum and cassiterite tin oxide nanoparticles with carbon support (J‐Pt@SnO2/C). Based on the synchrotron fine structure analysis and electrochemical investigation, the crystalline reconstruction and charge redistribution at the interface of Janus structure are revealed. The tightly coupled interface could optimize the valance states of Pt and the adsorption/desorption of oxygenated intermediates. As a result, the J‐Pt@SnO2/C catalyst possesses distinguishing long‐term stability during the accelerated durability test without obvious degradation after 40 000 cycles and keeps the majority of activity after 70 000 cycles. Meanwhile, the catalyst exhibits outstanding activity with half‐wave potential at 0.905 V and a mass activity of 0.355 A mgPt−1 (2.7 times higher than Pt/C). The approach of the Janus catalyst paves an avenue for designing highly efficient and stable Pt‐based ORR catalyst in the future implementation.

Feng Y., Xie J., Zhao G., Li X., Wang J., Ding W., Wei Z.

Developing a fast diagnostic technology for membranes and accurately predicting the lifetime of membranes that can effectively reduce the manufacturing cost and overcome the technical barriers of proton exchange membrane fuel cell (PEMFC) lifetime. This paper focuses on developing an ex-situ accelerated chemical degradation method and investigating the impact of chemical degradation on membrane structure and fuel cell performance. The results show that voltage drop and hydrogen permeation current can detect the state online and predict the remaining lifetime of membrane electrode assembly (MEA). The aging rate is faster by three orders of magnitude than that of the published results by the established aging way. This study provides an additional decision for evaluating performance degradation and fuel cell system optimization, which could potentially lead to further improvements in the efficiency and durability of PEMFC systems.

Boretti A.

Jithul K.P., Tamilarasi B., Pandey J.

Green hydrogen–fueled low-temperature proton exchange membrane (PEM) fuel cells have emerged as one of the most attractive technologies for electric-vehicle (EV) applications due to their high efficiency, zero emissions, and potential for renewable energy integration. The performance of the PEM fuel cells is significantly affected by the electrochemical activity of the oxygen reduction reaction (ORR) catalyst. This review comprehensively examines the role of ORR electrocatalysts in PEM fuel cell efficiency for portable, transport, and stationary applications. In this direction, we discuss the fundamentals of PEM fuel cell operation, the critical role of electrocatalysts, and advanced characterization techniques. A detailed overview of ORR electrocatalyst types, including platinum-based, non-noble metal-based, and carbon-supported as well as noncarbon supported, is presented, emphasizing recent advancements in design and synthesis. The review concludes with discussing current challenges and future directions for ORR electrocatalyst development. Understanding the characteristics and recent developments of ORR catalysts is essential for researchers and engineers to optimize the performance and durability of PEM fuel cells, thereby promoting the wider adoption of clean and efficient energy technologies. By providing insights into electrocatalyst characteristics and emerging trends, this work aims to accelerate the adoption of clean and efficient PEM fuel cell technology.

Klokova K.S., Ardabevskaia S.N., Katarzhnova E.Y., Milenin S.A., Muzafarov A.M.

The review considers several aspects of the synthesis of dendrimers related to the efficient achievement of their mass and high functionality. These are synthetic methods based on a block scheme for the production of dendrimers and click reactions in the processes of dendritic growth. A method for the synthesis of dendrimers, in which their rapid growth and size are achieved through the use of long spacers between branch points, is also considered. In general, all of these approaches are aimed at the formation of highly functional or high molecular weight molecules with a dendrimer structure in a short time.

Evro S., Oni B.A., Tomomewo O.S.

Bayan Y., Paperzh K., Pankov I., Alekseenko A.

There are numerous carbon materials that are deemed promising for use as supports in electrocatalysts for PEMFCs. We have carried out a comparative analysis of compositional, morphological and electrochemical characteristics of the platinum–carbon catalysts synthesized by a single method on various carbon supports (Vulcan XC-72, Ketjenblack EC-300 J, Ketjenblack EC-600JD and N-doped Ketjenblack EC-600JD) and the commercial electrocatalyst. The Pt/C materials obtained on highly dispersed supports (from 800 m2 g−1) exhibit almost 1.5 times greater ORR activity compared to those with a specific surface area of less than 250 m2 g−1. Doping of a highly dispersed support with nitrogen leads to a 30 % increase in the durability of the catalysts based thereon. The resulting Pt/C on the N-doped support exhibits an ESA of more than 110 m2 g−1 and an ORR mass activity of about 430 A g-1Pt, which correspond to the DOE targets and are 1.6 and 1.7 times higher than those of the commercial analog.

Gu H., Peng C., Qian Z., Lv S., Feng J., Luo K., Zhan M., Xu P., Xu X.

Proton exchange membrane fuel cell (PEMFC) is considered as a highly efficient and clean energy conversion technology, however, as the power density increases, conventional gas channels exhibit low mass transfer efficiency and high pumping power consumption. In this study, a novelly designed structure of gas channel with groove baffles is proposed, and a numerical simulation of three-dimensional, multi-physical field is conducted. The traditional smooth flow channel and the rectangular baffled channel are compared with the groove baffled channel. It is found that the pressure drop of the groove baffled channel is substantially less than the rectangular baffled channel, and the current density is higher than that of the traditional smooth flow channel. To obtain the optimal structural parameter of the groove baffle, the genetic algorithm is applied in this study. According to the results, the optimal comprehensive output performance of the cell is achieved for a groove height and width of 0.479 mm and 0.841 mm, respectively. At an operating potential of 0.5 V, the power density of PEMFC with the optimal structure is 3.2 % more than the traditional smooth flow channel. While compared with the rectangular baffled channel, the pumping power consumption is 53.6 % much lower and the overall efficiency is 2.1 % higher for the optimal groove baffled channel. This study will provide guidance for the design and optimization of the PEMFC's gas channels.

Zhang S., Xiong Y., Wang Y., Ma Y., Li J., Jiang C., Wang C., Zhu Y., Zhao Y., Zhang G.

AbstractPolyurea (PU) elastomers have attracted considerable attention in the field of protective polymeric coatings. In this work, a dithiol‐terminated boronic ester was synthesized and used to incorporate dynamic boron–oxygen (B–O) bonds in the PU main chain based on thiol isocyanate while amino‐terminated polydimethylsiloxane (PDMS) was introduced to retain good chain flexibility. The modified PU elastomer was found to have a microphase‐separated structure in which the hard blocks served as physical crosslinks. The glass transition temperature (Tg) slightly increases when dynamic B–O bonds exist while further introduction of PDMS soft segment can lower Tg to −55.63 °C. The introduction of dynamic B–O bonds and diminished hydrogen bonding led to a decrease in mechanical strength and elongation at break. Interestingly, the simultaneous incorporation of PDMS and dynamic B–O bonds is favorable for strain rate dependence and suppressing stress relaxation. The potential for bond‐exchange interactions between the dynamic B–O bonds and hydroxyl groups on metal surfaces substantially improved the adhesion of the PU elastomer to metal substrates. Therefore, our work can offer valuable insights for the structural design of functional PU coatings tailored for anti‐impact applications. © 2024 Society of Chemical Industry.

Zhang T., Shi Y., Chen W., Huang J., Li C.

Self-healing and recyclable polymer elastomers are being developed to provide new prospects in building sustainable societies. Nevertheless, the synthesis of such materials still poses a significant difficulty because of the conflicting requirements between the self-healing ability and mechanical robustness for the dynamicity of crosslinks. Herein, a self-healing and recyclable supramolecular polydimethylsiloxane with outstanding tensile stress and ultrahigh mechanical toughness is constructed by synergistically incorporating dynamic disulfide bonds and multiple hydrogen bonds into a siloxane chain. The adipic dihydrazide (AD) bearing two hydrazide groups was appropriate introduced to provide multiple hydrogen bonding sites between polymer chains and improve the mechanical robustness of the crosslinked structure. The aromatic disulfide bonds contribute to shorter healing time due to the elevated dynamicity of the crosslinked network. The resulting elastomers exhibit high tensile strength (6.44 ± 0.24 MPa), distinguished toughness (37.00 ± 0.85 MJ m−3), superior elastic restorability, outstanding self-healing capability (∼86 %) and multiple recyclability. Furthermore, a bifunctional sensor based on this elastomer is constructed to monitor human motions and pressure changes, demonstrating the potential application in flexible stretchable electronics.

Wei S., Wu J., Gu X., Shen S., Ma M., Shi Y., He H., Zhu Y., Chen S., Wang X.

Polyurethane have the advantages of convenient structural design, low production cost, and excellent mechanical compatibility, and is expected to be used as a polymer heart valve material. However, its development in biomaterials is limited because it is prone to hydrolysis and coagulation after long-term implantation in organisms. In this study, "PEG-MDI-PEG" macromolecular diol was prepared by structural design of the soft segment of polyurethane. Copolymerization with telechelic α,ω-bis(6-hydroxyethoxypropyl)-PDMS as mixed soft segment, prepolymer solution was prepared by solution polymerization, and the biocompatibility of silicone-based polyurethane obtained by casting was characterized. By adjusting the feed ratio to control the silicon content in the copolymer, when the silicon content was 60%, the protein adsorption capacity was 75% lower than that of unmodified polyurethane, and the cell activity was more than 80%, which was a useful characteristic for silicon-based polyurethane as a potential polymer valve material.