19 research outputs found

    Synthesis of π-Conjugated Poly(cyclodiborazane)s by Organometallic Polycondensation

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    Donor−acceptor type π-conjugated poly(cyclodiborazane)s were synthesized by organometallic polycondensation between cyclodiborazane-containing dibromide and 2,5-didodecyloxy-1,4-diethynylbenzene utilizing Sonogashira coupling. The polymerization was carried out under a nitrogen atmosphere, in THF/NEt3 solution in the presence of a catalytic amount of copper acetate, palladium chloride, and triphenylphosphine at 80 °C for 12 h. After reprecipitation into MeOH, the resulting polymer was isolated as a brown powder in moderate yield. The polymer obtained was soluble in common organic solvents such as THF, chloroform, and benzene, and its structure was confirmed by 1H NMR, 11B NMR, and IR spectra. The number-average molecular weight of the polymer was 8500 from the gel permeation chromatographic analysis (GPC, THF, PSt standards). In the UV−vis absorption spectrum recorded in chloroform, the absorption maximum was observed at 414 nm, owing to extension of π-conjugation via the vacant p-orbital of the boron atom and intramolecular charge transferred structure. This polymer exhibited an intense blue-green light emission upon irradiation at 414 nm

    Charge–Discharge Behavior of Lithium-Ion Batteries Using a Polymer Electrolyte Bearing High-Density Functional Groups

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    Lithium-ion batteries (LIBs) have become crucial for various applications, but carbonate-based liquid solvents, commonly used in their electrolytes, suffer from the flammability and exchange dynamic of lithium-ion movement in electrolytes. To address these issues, poly­(ethoxycarbonylmethylene) (PECM) with a dense distribution of functional ester groups was evaluated as a polymer electrolyte in LIBs. The polymer was shown to be polar aprotic with an ET(30) value of 43.85 kcal mol–1 and to offer improved solvation of cations. Polymer electrolytes (PEs) in combination with LiTFSI showed a glass transition temperature in the range of 10–33 °C. PEs demonstrated good ionic conductivity within the range of 9.76 × 10–5–3.08 × 10–4 S cm–1 at 51 °C, lithium-ion transference number between 0.80 and 0.98, and activation energy of diffusion within 27.4–43.0 kJ mol–1. The PECM-based cathodic half-cell exhibited good rate capacity at varied current densities, and long-cycle performance showed 80% capacity retention at 0.2 C for more than 100 cycles. The effect of polarity on the conductivity and transport number and interfacial compatibility with the cathode show promise as an alternative electrolyte material for future lithium-ion battery applications

    Extension of π-Conjugation Length via the Vacant p-Orbital of the Boron Atom. Synthesis of Novel Electron Deficient π-Conjugated Systems by Hydroboration Polymerization and Their Blue Light Emission

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    Extension of π-Conjugation Length via the Vacant p-Orbital of the Boron Atom. Synthesis of Novel Electron Deficient π-Conjugated Systems by Hydroboration Polymerization and Their Blue Light Emissio

    π-Conjugated Poly(cyclodiborazane)s with Intramolecular Charge Transferred Structure

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    π-Conjugated Poly(cyclodiborazane)s with Intramolecular Charge Transferred Structur

    Heavy-Duty Performance from Silicon Anodes Using Poly(BIAN)/Poly(acrylic acid)-Based Self-Healing Composite Binder in Lithium-Ion Secondary Batteries

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    Natural abundance and high theoretical capacity make silicon a promising anode material in Li-ion batteries (LIBs). However, repeated cycling causes the pulverization of Si particles due to the large volume expansion that results in their rapid breakdown, delamination from the current collector, loss of electrical contact, and thick solid–electrolyte interphase (SEI) formation. This results in their poor performance. To overcome these drawbacks, the application of functional polymers as binders to silicon anodes has emerged as a competitive strategy. In this regard, here, the design, synthesis, and application of a highly robust n-type self-healing polymer composite poly­(bisiminoacenaphthenequinone)/poly­(acrylic acid) (P-BIAN/PAA) as a binder for Si anodes is reported. On its application, P-BIAN/PAA was evaluated to (i) provide mechanical robustness to the large volume expansion of Si particles, (ii) maintain electrical conductivity within the electrode laminate, and (iii) facilitate the formation of a thin SEI by restricting the extent of electrolyte decomposition on the surface of anode because of its low-lying lowest unoccupied molecular orbital (LUMO) that empowers its n-doping in the reducing environment. As a result, Si anodes could be stabilized for over 600 cycles of charge–discharge with a high reversible capacity of about 2100 mAh g–1Si, ∼95% capacity retention, and >99% Coulombic efficiency. The extent of suppression of electrolyte decomposition that led to a facile and thin interphase-SEI and the corresponding interfacial components with respective impedance values were not only theoretically evaluated but also supported by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and dynamic-EIS. Further, the postmortem characterization of the anode by X-ray photoelectron spectroscopy (XPS) justified the thin SEI formation on Si anode with P-BIAN/PAA composite binder

    Synthesis of Poly(cyclodiborazane)s Bearing a Disilanylene Unit and Their Optical and Electrochemical Properties

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    Synthesis of Poly(cyclodiborazane)s Bearing a Disilanylene Unit and Their Optical and Electrochemical Propertie

    Selective Ion Transport in Organoboron Polymer Electrolytes Bearing a Mesitylboron Unit

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    Selective Ion Transport in Organoboron Polymer Electrolytes Bearing a Mesitylboron Uni

    Alternating Poly(borosiloxane) for Solid State Ultrasensitivity Toward Fluoride Ions in Aqueous Media

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    Facile synthesis of alternating copolymer poly­(borosiloxane) via dehydrocoupling was successfully carried out in the presence of transition metal catalyst at room temperature. The polymer was characterized by NMR and IR spectroscopy. The presence of a single peak in <sup>11</sup>B NMR and <sup>29</sup>Si NMR supported the alternating sequence of the polymer which was further complimented by the study of specifically designed model reactions. Fluoride ion sensitivity was analyzed by electrochemical methods.. The anion selective electrode prepared using synthesized polymer was found to be extremely sensitive toward fluoride ions (10<sup>–10</sup> M in aqueous media) by potentiometric measurements using 0.1 M disodium hydrogen phosphate as supporting electrolyte, Ag/AgCl as reference electrode, and Pt wire as counter electrode

    BIAN-Based Porous Organic Polymer as a High-Performance Anode for Lithium-Ion Batteries

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    Lithium-ion batteries are heralded as potential candidates for large-scale energy storage applications. The low specific capacity or poor cyclability of commonly used anodes limit the extensive application of lithium-ion batteries. In this context, organic molecules can offer a potential solution to extend the scope of lithium-ion battery application. In this work, we demonstrate the synthesis and electrochemical properties of a nitrogen-rich, n-type porous organic polymer bearing BIAN and melamine moieties (PBM). The PBM exhibits a porosity of 1.5 nm and excellent electrochemical performance in terms of its rate capability, cycling behavior, and capacity. The anodic half-cell of the PBM active material delivers specific capacities of 850 mAh/g at 400 mA/g, 740 mAh/g at 750 mA/g, and 300 mAh/g at 1000 mA/g current densities with an excellent cyclability over 3000, 2000, and 1100 cycles, respectively, at each current density. Thus, this material is a promising candidate as an anodic material in lithium-ion batteries

    BIAN Based Electroactive Polymer with Defined Active Centers as Metal-Free Electrocatalysts for Oxygen Reduction Reaction (ORR) in Aqueous and Nonaqueous Media

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    We report design, synthesis, and performance evaluation of functional polymer material with defined active sites for oxygen reduction reaction (ORR) catalytic activity in aqueous as well as nonaqueous media. The BIAN-paraphenylene (BP) copolymer having an imine backbone was synthesized via solution based polycondensation. The as synthesized polymer itself showed ORR activity comparable to that of other doped carbon materials. The composites of the polymer with graphene oxide (GO) sheets (GO/BP) were also synthesized under moderate temperature conditions (400 °C) with the polymer remaining intact. The composites showed further enhanced electrochemical activity owing to the synergistic effect of GO and active site defined polymer material. We also tried to evaluate the nature and basis of catalytic activity on the polymer surface by different techniques. The cyclic voltammograms showed two distinct ORR peaks, indicating two different active sites. This was also in agreement with Mulliken charge distribution from DFT studies, which showed the presence of two different carbons next to nitrogen having different electropositive nature
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