Hyteroatoms Si, P, S as possible factors for the formation of the structure of pyrolyzed carbon materials

The aim of the study was to investigate the effect of heteroatoms on the deformation of graphene, as well as on the formation of the Stone-Wallace defect. To date, research on processes involving nanocarbon materials is relevant. In particular, in the formation of fullerenes, nanoonions and a number of other carbon nanoforms, the five-membered carbon cycles (pentactagonis) of the hepatogenesis (pentactagon) play the most important role in the curvature of initially flat graphene sheets and the formation of fullerene-like structures in the form of closed, skeletal, macromolecular formations. It should be noted, however, that the Pentagon is not the only factor in distorting the flat structure of graphene sheets in layered carbon materials. Some other defects of the carbon lattice (in particular, seven-membered carbon cycles and heteroatoms of a number of nonmetals with covalent radii exceeding the radius of the carbon atom) may play a similar role to one degree or another. These heteroatoms (primarily Si, P, S) are usually part of the precursors of mineral or vegetable origin and can be embedded in the carbon lattice in the process of coal production. Stone-Wallace there is their mutual compensation and preservation of a flat structure. The calculations were performed using quantum chemical modeling of doped nanographs in clusters of different size, composition and morphology, using the theory of density functional (DFT) with exchange-correlation functional B3LYP, based on the extended valence-split basis 6-31G (d) with full optimism clusters using the Firefly software package. It has been found that heteroatoms of non-metals with covalent radii exceeding the radius of the C atom, which are usually present in the precursors of mineral or vegetable origin used to produce pyrolyzed carbon materials, can play a significant role in energy. a number of nanoforms of carbon, activated carbon and other pyrolyzed nanostructured carbon materials.

Doubly linked chiral phenanthrene oligomers for homogeneously π-extended helicenes with large effective conjugation length

Helically twisted conductive nanocarbon materials are applicable to optoelectronic and electromagnetic molecular devices working on the nanometer scale. Herein, we report the synthesis of per-peri-perbenzo[5]- and [9]helicenes in addition to previously reported π-extended [7]helicene. The homogeneously π-extended helicenes can be regarded as helically fused oligo-phenanthrenes. The HOMO−LUMO gap decreased significantly from 2.14 to 1.15 eV with increasing helical length, suggesting the large effective conjugation length (ECL) of the π-extended helical framework. The large ECL of π-extended helicenes is attributed to the large orbital interactions between the phenanthrene subunits at the 9- and 10-positions, which form a polyene-like electronic structure. Based on the experimental results and DFT calculations, the ultrafast decay dynamics on the sub-picosecond timescale were attributed to the low-lying conical intersection.

Mixed sp2–sp3 Nanocarbon Materials: A Status Quo Review

Carbon nanomaterials with a different character of the chemical bond—graphene (sp2) and nanodiamond (sp3)—are the building bricks for a new class of all-carbon hybrid nanomaterials, where the two different carbon networks with sp3 and sp2 hybridization coexist, interacting and even transforming into one another. The extraordinary physiochemical properties defined by the unique electronic band structure of the two border nanoallotropes ensure the immense application potential and versatility of these all-carbon nanomaterials. The review summarizes the status quo of sp2 – sp3 nanomaterials, including graphene/graphene-oxide—nanodiamond composites and hybrids, graphene/graphene-oxide—diamond heterojunctions, and other sp2–sp3 nanocarbon hybrids for sensing, electronic, and other emergent applications. Novel sp2–sp3 transitional nanocarbon phases and architectures are also discussed. Furthermore, the two-way sp2 (graphene) to sp3 (diamond surface and nanodiamond) transformations at the nanoscale, essential for innovative fabrication, and stability and chemical reactivity assessment are discussed based on extensive theoretical, computational and experimental studies.

Analysis of Shape Memory Behavior and Mechanical Properties of Shape Memory Polymer Composites Using Thermal Conductive Fillers

Shape memory polymers (SMPs) are attracting attention for their use in wearable displays and biomedical materials due to their good biocompatibility and excellent moldability. SMPs also have the advantage of being lightweight with excellent shape recovery due to their low density. However, they have not yet been applied to a wide range of engineering fields because of their inferior physical properties as compared to those of shape memory alloys (SMAs). In this study, we attempt to find optimized shape memory polymer composites. We also investigate the shape memory performance and physical properties according to the filler type and amount of hardener. The shape memory composite was manufactured by adding nanocarbon materials of graphite and non-carbon additives of Cu. The shape-recovery mechanism was compared, according to the type and content of the filler. The shape fixation and recovery properties were analyzed, and the physical properties of the shape recovery composite were obtained through mechanical strength, thermal conductivity and differential scanning calorimetry analysis.

Nanocarbon-Based Flame Retardant Polymer Nanocomposites

In recent years, nanocarbon materials have attracted the interest of researchers due to their excellent properties. Nanocarbon-based flame retardant polymer composites have enhanced thermal stability and mechanical properties compared with traditional flame retardant composites. In this article, the unique structural features of nanocarbon-based materials and their use in flame retardant polymeric materials are initially introduced. Afterwards, the flame retardant mechanism of nanocarbon materials is described. The main discussions include material components such as graphene, carbon nanotubes, fullerene (in preparing resins), elastomers, plastics, foams, fabrics, and film–matrix materials. Furthermore, the flame retardant properties of carbon nanomaterials and their modified products are summarized. Carbon nanomaterials not only play the role of a flame retardant in composites, but also play an important role in many aspects such as mechanical reinforcement. Finally, the opportunities and challenges for future development of carbon nanomaterials in flame-retardant polymeric materials are briefly discussed.

Deep-red circularly polarised luminescent C70 derivatives

Optically active fullerenes, including C60 and C70 derivatives carrying organic substituents, are used in a range of applications because of their unique spectroscopic, catalytic, and chiral recognition properties. However, their inherent photoexcited chirality is yet to be elucidated because of their very poor fluorescence quantum yield (Φf). We synthesised a new chiral C70 derivative, X70A, with 20% yield, by reacting bis-borylated xanthene with C70 in a one-step double addition reaction, followed by a successful optical resolution. The isolation of two separate X70A enantiomers was confirmed by mirror-image circular dichroism spectroscopy in the range of 300–750 nm. In toluene, the enantiomeric pair of X70A clearly revealed mirror-image circularly polarised luminescence (CPL) spectra with a high |glum| value of 7.0 × 10−3 at 690 nm. The first fullerene-based deep-red CPL of X70A should provide a new guideline for the design of chiral nanocarbon materials.

Tuning Electronic Structure and Optical Properties of Li@cyclo[18]carbon Complex via Switching Doping Position of Lithium Atom

Doping alkali metal atoms, especially lithium (Li), in nanocarbon materials has always been considered as one of the most effective methods to improve the optical properties of the system. In this theoretical work, we doped a Li atom into the recently observed all-carboatomic molecule, cyclo[18]carbon (C₁₈), and finally obtained two stable configurations with Li inside and outside the ring. The calculation results show that the energy barrier of transition between the two Li@C₁₈ complexes is quite low, and thus the conversion is easy to occur at ambient temperature. Importantly, the electronic structure, absorption spectrum, and optical nonlinearity of the two configurations are found to be significantly different, which indicates that the electronic structure and optical properties of the Li@C₁₈ complex can be effectively regulated by switching the location of the doped Li atom between inside and outside the carbon ring. With the help of a variety of wave function analysis techniques, the nature of the discrepancies in the properties of the Li@C₁₈ complex with different configurations has been revealed in depth. The relevant results of this work are expected to provide theoretical guidance for the future development of cyclocarbon-based optical molecular switches.