Synthesis and characterization of high-softening-point methylene-bridged pitches by visible light irradiation assisted free-radical bromination

Ge, Chuanzhang; Hu, Yang; Miyawaki, Jin; Mochida, Isao; Yoon, Seong Ho; Qiao, Wenming; Long, Donghui; Ling, Licheng

doi:10.1016/j.carbon.2015.09.003

Cited by 42 publications

(15 citation statements)

References 32 publications

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“…The MALDI-TOF mass spectra of NPs are shown in Figure b. All the spectra consist of a series of march-past clusters centered at 205, 302, 387, 545, and 677 Da, etc., indicating the presence of substituted naphthalene, dimers, trimers, and oligomers carried some extra hydrogens and fragments . These oligomers result in broad molecular weight distribution curves for NPs.…”

Section: Resultssupporting

confidence: 85%

“…128 ( m / z ) by incremental analysis, which is close to the molecular weight of naphthalene (Mw = 128.1). Moreover, analogous spans for each cluster especially in NP 125 are observed such as from 520 to 571 Da, from 654 to 696 Da, from 781 to 832 Da, and from 908 to 949 Da, revealing that many oligomers attend to lose or to capture some substituent groups deviating from their ideal structure . The result is consistent with the observed result from FTIR of NPs.…”

Section: Resultsmentioning

confidence: 99%

“…All the spectra consist of a series of march-past clusters centered at 205, 302, 387, 545, and 677 Da, etc., indicating the presence of substituted naphthalene, dimers, trimers, and oligomers carried some extra hydrogens and fragments. 22 These oligomers result in broad molecular weight distribution curves for NPs. Meanwhile, the strongest peak and the ones with higher abundance shift toward higher molecular weight in the order of NP 25 , NP 75 , and NP 125 , suggesting that the oligomers of larger molecules are formed with the increasing of CHCl 3 content.…”

Section: ■ Materials and Methodsmentioning

confidence: 99%

See 2 more Smart Citations

Template-Free Synthesis of Honeycomblike Porous Carbon Rich in Specific 2–5 nm Mesopores from a Pitch-Based Polymer for a High-Performance Supercapacitor

Guan

Zhao

Zhang

et al. 2018

ACS Sustainable Chem. Eng.

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A template-free strategy has always been attractive to design and fabricate advanced carbon materials with tunable nanostructures from cheap precursors. Herein, honeycomblike mesoporous carbons (HPCs) are prepared from pitch-based polymers through a self-assembly foaming strategy without using any templates. Rich mesopores specific in sizes of 2–5 nm and abundant open-ended honeycomblike holes endow a hierarchical pore-in-pore feature of HPCs and an ultrahigh specific surface area (3473 m2 g–1). With their superior structure, HPCs can deliver a high supercapacity of 339 F g–1 at a current density of 1 A g–1 in 6 M KOH aqueous electrolyte and retain 85.6% of the capacity even at a current density of 50 A g–1. Meanwhile, a supercapacitive cell assembled by two HPC electrodes yields a conspicuously ultrahigh energy density of 34.5 Wh kg–1 (12.8 Wh L–1) at a high power density of 679.4 W kg–1 (251.4 W L–1). This work provides a new method for the controllable synthesis of advanced carbon materials from pitch and presents further applications in flexible electrochemical supercapacitors.

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Section: Resultssupporting

confidence: 85%

Section: Resultsmentioning

confidence: 99%

Section: ■ Materials and Methodsmentioning

confidence: 99%

See 1 more Smart Citation

Template-Free Synthesis of Honeycomblike Porous Carbon Rich in Specific 2–5 nm Mesopores from a Pitch-Based Polymer for a High-Performance Supercapacitor

Guan

Zhao

Zhang

et al. 2018

ACS Sustainable Chem. Eng.

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“…The 13 C NMR spectra of P230 and T230 are presented in Figure , and the distributions of aromatic and aliphatic carbons are listed in Table . Both pitches carry a considerable amount of methylene hydrogen, which are consistent with the characteristics of dehydrobromination pitches . P230 possesses 34.70% protonated aromatic carbons compared to 47.69% found in T230.…”

Section: Results and Discussionsupporting

confidence: 75%

Controllable Synthesis of Highly Graphitizable Pitches from 1-Methylnaphthalene via Closed-System Dehydrobromination

Han

Wang

et al. 2018

Energy Fuels

Self Cite

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Novel graphitizable pitches with controllable softening points and methylene-bridged structures were successfully prepared through photobromination of 1-methylnaphthalene (1-MNa) followed by closed-system dehydrobromination (CSD). The structures of bromination products and dehydrobromination pitches were determined using gas chromatography–mass spectroscopy, NMR and laser desorption/ionization-time of flight/mass spectroscopy. It was found that the amount of bromine introduced greatly affected the composition of bromination products. 1-MNa brominated at a bromine/1-MNa molar ratio of 0.75 (BMNa-0.75) demonstrated the highest methyl bromination selectivity (S mb), which was selected as the dehydrobromination precursor. After a CSD/polymerization reaction under 200–250 °C, dehydrobromination pitches with softening points of 148–226 °C were acquired. Compared with open-system dehydrobromination (OSD), CSD endowed bromine radical longer life and boosted intramolecular and intermolecular linking, thereby substantially increasing softening points and coking values. The polymerization degree of CSD-derived pitches is highly regulable depending on dehydrobromination temperature and the amount of tetrahydronaphthalene (tetralin) introduced. Moreover, methyl migration products (naphthalene, 2-methylnaphthalene, dimethyl-naphthalene and trimethyl-naphthalene) together with hydrogenation products (mainly tetralin) were detected by analyzing the hexane-soluble components (HS). The structural features of CSD-derived pitches contributed to some unique properties such as high polymerization degree accompanied by low aromaticity, continuous molecular weight distribution and complex connection types among subunits including α–α′, α–β′, and β–β′. The semicoke with 94% anisotropy of coarse flow texture was synthesized at 420 °C under atmospheric pressure. Well-developed graphitic carbons with graphitization degree of 81.40% and I D/I G of 0.12 was obtained from graphitization of dehydrobromination pitches under 2600 °C.

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“…Additionally, the high reactivity characteristic also causes excessive polycondensation, resulting in the formation of insoluble coke and carbon particles, which affect the spinning performance. To improve the yield and prepare pitch precursors with good spinning performance, Ge et al [ 17 ] and Kim et al [ 18 ] proposed a method for preparing high quality pitch precursors with methyl naphthalene as the material by bromination-debromination. The polymer pitch consisted of numerous repeating monomers of methylene-bridged naphthalene rings with linear structures.…”

Section: Introductionmentioning

confidence: 99%

Effects of Bromination-Dehydrobromination on the Microstructure of Isotropic Pitch Precursors for Carbon Fibers

et al. 2020

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In this work, isotropic pitch precursors are synthesized by the bromination-debromination method with ethylene bottom oil (EO) as the raw material and bromine as the initiator for pitch formation and condensation reactions. The aggregation structure, molecular weight distribution, and molecular structure of isotropic pitch precursors are characterized by thermal mechanical analyzer (TMA), MALDI TOF-MS, and 13C NMR, respectively, for revealing the mechanism of synthesis of isotropic pitch precursors. The results show that at low bromine concentrations, polycyclic aromatic hydrocarbons (PAHs) were mainly ordered in cross-linked structures by bromination-debromination through substitution reactions of side chains. The condensed reactivity can be improved by the effect of bromine, meaning that condensation reaction was aggravated by the method of bromination-dehydrobromination. In the presence of excess bromine, the cross-linked stereo structure of PAHs changed to the planar structure of condensed PAHs, which was not conducive to the subsequent spinning and preparation of carbon fibers.

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Synthesis and characterization of high-softening-point methylene-bridged pitches by visible light irradiation assisted free-radical bromination

Cited by 42 publications

References 32 publications

Template-Free Synthesis of Honeycomblike Porous Carbon Rich in Specific 2–5 nm Mesopores from a Pitch-Based Polymer for a High-Performance Supercapacitor

Template-Free Synthesis of Honeycomblike Porous Carbon Rich in Specific 2–5 nm Mesopores from a Pitch-Based Polymer for a High-Performance Supercapacitor

Controllable Synthesis of Highly Graphitizable Pitches from 1-Methylnaphthalene via Closed-System Dehydrobromination

Effects of Bromination-Dehydrobromination on the Microstructure of Isotropic Pitch Precursors for Carbon Fibers

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