Polyacrylonitrile-Coated Onion-like Carbon Nanoparticles for Carbon Nanofibers with Enhanced Strength and Toughness

Abstract

Due to the typical strong and tough graphitic structures, carbon nanofibers (CNFs) theoretically have excellent mechanical properties. However, in practice, the defects and misalignments in these crystal domains always jeopardize the performance of CNFs and limit their further application. In this case, this paper takes onion-like carbon (OLC) as an effective nanofiller to optimize the fiber graphitic structure and produces composite CNFs with enhanced strength and toughness. For this purpose, the in situ polymerization technique is specially developed for the rapid and uniform distribution of OLC in the polyacrylonitrile (PAN) precursor of CNFs. The obtained PAN-coated OLC nanoparticles successfully avoid the agglomeration of nanofillers and can be further electrospun into OLC uniformly doped PAN nanofibers. Owing to the interaction between OLC and PAN matrix, the crystal domains in PAN precursor nanofibers are thicker and transformed from integrated shish-kebab structures into nanofibril crystals with better regularity and orientation. In the subsequent stabilization and carbonization processes, these crystalline nanofibrils are considered to be the structural basis for the formation of oriented and continuous graphitic domains in final CNFs. Meanwhile, the graphitic shells of OLC are confirmed to act as the template in the carbonization process to induce and promote the crystallization of the surrounding fiber matrix and transform the turbostratic structures in fiber crystal domains into more orderly graphitic structures with increased size and continuity. Furthermore, the embedded nanoscale OLC can co-move and continuously interact with the resulting graphitic domains during the deformation process for load transfer. As a result, the tensile strength and elongation at break of OLC-reinforced CNFs increase by 53.5 and 34.0%, respectively. The strong and tough composite CNFs may help to avoid the potential fiber breaking in their practical use and be further applied in wearable capacitors, masks, filters, etc.

In Situ Synthesis of Self-Assembly Supramolecular Crystal Seeds within Continuous Carbon Nanofibers for Improved Fiber Graphitic Structure

“…Compared with our existing work (Table S3), the reinforcement effects of both DC/DMF and TB/DMF on the strength of CNFs are comparable to or even better than that of the reported carbonaceous additives such as GO, onion-like carbon, nanographite, and so forth. ,− In this case, given the rather low cost and simple synthesis methods of such self-assembled supramolecular seeds without additional dispersion processes to avoid agglomeration, their application is more suitable for the large-scale production of high-performance carbon-based fibers.…”

“…The sample structures were characterized via a FTIR system (FTIR-650, GANG DONG, China), X-ray diffractometer (SmartLab 9 kW, Rigaku Corporation, Japan), an elemental analyzer (UNICUBE, Elementar, Germany), a thermogravimetric analyzer (TGA/DSC 3+, METTLER TOLEDO, Switzerland), a nanoparticle size analyzer (90Plus Zeta, Brookhaven, USA), and a Raman spectrometer (DXR2xi, Thermo Fisher, USA). Finally, the mechanical properties of carbonized nanofiber strips were tested via an XQ-1C tensile tester from Donghua University in China, as in our previous work. ,− …”

“…The small-molecule comonomers and cross-linking agents are nowadays well-established additives that play an active role within/between the molecular chains of PAN precursors. ,, As the research progresses, more studies are focusing on large-scale additives with more complex structures, among which the carbonaceous additive (such as CNTs, graphene, and their derivatives) is one of the most successful applications. ,, Numerous studies have revealed that carbonaceous additives can induce the ordered arrangement and orientation of PAN molecular chains and promote their aromatization reaction in the stabilization process as well as the subsequent graphitization process during carbonization through nucleating and templating effects, which finally lead to improved graphitic structures and various properties of carbon-based fibers. ,,− Based on systematical experiments and simulations on graphene oxide (GO)-doped fibers, Gao et al reveal the in-depth mechanism of the nucleating and templating actions of the carbonaceous additive . Their research proposes the core concepts of topological mismatch and modulation in the preparation of high-performance carbon-based fibers and illuminates the 2D seeded graphitization mechanism of GO to promote the growth of oriented and ordered graphitic domains within fibers, laying a theoretical foundation for the development of carbonaceous additives. ,− Overall, there are still three key issues that limit the further application of carbonaceous additives in the large-scale production of advanced carbon-based fibers: (a) high cost, (b) strong agglomeration tendency, and (c) weak interaction with the fiber matrix. − …”

Nickel modified TiO2/C nanodisks with defective and near‐amorphous structure for high‐performance sodium‐ion batteries

“…The Ti 2p spectrum of TC has two peaks at 458.8 and 464.6 eV, typical of Ti 4+ 2p 3/2 and Ti 4+ 2p 1/2 peaks. 34 In contrast, the Ti 2p peaks of 10N-TC shifted slightly towards the direction of low-binding energy, which is due to the enhanced electron screening effect of Ti cores by OVs. 35 This variation can also be traced from the Ti 2p spectra of 5N-TC and 15N-TC (Supporting Information S1: Figure 4A).…”

Ultrasensitive electrochemical immunosensor for the detection of C-reactive protein antigen

“…Inspired by the promising vision of electrochemical immunosensing of carbon-based nanomaterials, OLC is anticipated to have a significant immunosensor performance because of their characteristic concentric spherical crystal, and graphitic structures. 39 Herein, we develop onion-like carbon integrated with polyacrylonitrile (OLC-PAN) nanocomposite as a viable platform for the detection of CRP using an electrospinning technique. The combination of OLC and PAN offers a compelling sensing matrix due to their synergistic properties.…”