Diamond Nanothreads Research Articles

Insights on the Bonding Mechanism, Electronic and Optical Properties of Diamond Nanothread-Polymer and Cement-Boron Nitride Nanotube Composites.

The success of composite materials is attributed to the nature of bonding at the nanoscale and the resulting structure-related properties. This study reports on the interaction, electronic, and optical properties of diamond nanothread/polymers (cellulose and epoxy) and boron nitride nanotube/calcium silicate hydrate composites using density functional theory modeling. Our findings indicate that the interaction between the nanothread and polymer is due to van der Waals-type bonding. Minor modifications in the electronic structures and absorption spectra are noticed. Conversely, the boron nitride nanotube-calcium silicate hydrate composite displays an electron-shared type of interaction. The electronic structure and optical absorption spectra of the diamond nanothread and boron nitride nanotube in all configurations studied in the aforementioned composite systems are well maintained. Our findings offer an electronic-level perspective into the bonding characteristics and electronic-optical properties of diamond nanothread/polymer and boron nitride nanotube/calcium silicate hydrate composites for developing next-generation materials.

Diamond Nanostructures at Different Dimensions: Synthesis and Applications

AbstractDiamond materials at different nanoscales provide them various characteristics such as elastic mechanical properties in needle‐like nanotips, flexibility of 2D films having atomic thicknesses and constant hardness under high pressures, superior field electron emission properties of vertically wall‐like composites, unprecedented hardness and improved toughness of nanotwin diamond (nt‐diamond), while the inherent excellent properties of bulk diamond (e.g., high Young's modulus, robustness, biocompatibility) can be maintained. In this paper, the newly born 1D diamond nanothreads, 2D diamanes, as well as 3D nt‐diamond are briefly reviewed. The innovations, progresses and achievements of different dimensional diamond nanostructures, covering lines, planes and volumes are overviewed. The topical problems and future outlooks of diamond nanostructures are outlined and discussed.

Impact of diamond nanothread on the viscosity of asphalt binder: Insights from atomistic simulations

Viscosity stands as a pivotal property within asphalt binder, exerting influence not only over the pavement quality and construction efficiency but also over energy consumption and harmful gas emissions. Lower viscosity at the mixing temperature can reduce the energy consumption and emissions remarkably. As such, extensive efforts have been devoted to tailor the viscosity of asphalt by adding nanomaterials. Through atomistic simulations, this work provides an in-depth assessment on the viscosity of asphalt binder modified by ultrathin diamond nanothread (DNT). It is observed that the addition of DNT can reduce the viscosity of asphalt, a phenomenon traced back to the sp3-bonded nature of DNT that prevents the formation of π - π bonds with asphaltene molecules. Notably, samples endowed with higher count of stacked asphaltene molecules tend to display higher viscosity. Further investigation reveals that the sample with aggregated DNTs exhibits a lower viscosity, as the aggregated DNTs exert a more subdued influence on asphalt molecule mobility. Specifically, DNTs are found to promote the mobility of all molecules, and a remarkable enhancement on the mobility of saturated molecules is observed. This distinct behavior sets them apart from single-walled carbon nanotubes (SWNTs), where viscosity rises with increasing content due to the SWNT-induced aggregation of asphaltene molecules. Overall, this work unveils the intricate mechanisms influencing the viscosity of asphalt binders through diamond nanostructures. These findings could be beneficial for the design of asphalt binders with tailored rheological properties.

Topology-controlled thermomechanical properties of diamond nanothread enhanced polymeric materials

Among carbon-based nanoadditive for polymeric materials, diamond nanothread (DNT) has attracted considerable interest due to its exceptional mechanical properties. However, the precise roles of DNT in the enhancement of thermomechanical properties are unknown. Here, the role of DNT with various topological structures on the glass transition temperature (Tg) of polymeric materials and the underlying mechanism of glass-rubber transition are identified utilizing molecular dynamics simulation. Interaction mechanism is discussed through density functional theory, which reveals influence of DNT topological structures on the instantaneous dipole at interface between DNT and adjacent polymer chains. Our results demonstrate that DNT with different topological structures processes variability in the enhancement of thermomechanical properties to the polymeric materials, which is related to rigidness, the dihedral angle between DNT and aromatic ring in the polymer chain, and the different mechanical interlock. The transition from glass to rubber is induced by increases in intermolecular motions, which is brought by increases in free volume at interface that are ruled by van der Waals interaction. It is also found that DNT significantly improves the Tg of epoxy nanocomposite more than other carbon-based nanoadditives. These findings reveal the thermal degradation mechanism of polymeric composite, also provide guidance for improving the reinforcing efficiency of nanomaterials in engineering applications. We anticipate our research to provide state-of-the-art theoretical approaches for the design of new nano-additives that are tailored to different reinforcement needs of polymeric composite.

Assessing the impact of ultra-thin diamond nanothreads on the glass transition temperature of a bituminous binder.

Low-temperature cracking and rutting are the most destructive problems of bitumen that hinder the application of high-performance bitumen engineering, which is dependent on its glass transition temperature (Tg). Through in silico studies, this work has systematically investigated the Tg of a bituminous binder with the addition of diamond nanothread (DNT) fillers with varying filler content, alignment, distribution, and functional groups. In general, the glass transition phenomenon of the bitumen is determined by the mobility of its constituent molecules. Tg is found to increase gradually with the increase in the weight percentage of DNT and then decreases when the weight percentage exceeds 5.05 wt%. The enhancement effect on Tg is weakened when DNTs are distributed vertically or functionalized with functional groups. Specifically, DNT fillers induce inhomogeneity, which promotes the motion of small molecules while hindering the motion of large molecules. The aggregation of DNTs and the molecular environment in the vicinity of DNTs directly affect Tg. In summary, aggregation and adhesion are the dominant mechanisms affecting the mobility of the constituent molecules in the DNT/bitumen system and thus its glass transition temperature. This work provides in-depth insights into the underlying mechanisms for the glass transition of a bituminous binder, which could serve as theoretical guidance for tuning the low-temperature performance of the bituminous binder.

From Biomass to Functional Crystalline Diamond Nanothread: Pressure-Induced Polymerization of 2,5-Furandicarboxylic Acid.

2,5-Furandicarboxylic acid (FDCA) is one of the top-12 value-added chemicals from sugar. Besides the wide application in chemical industry, here we found that solid FDCA polymerized to form an atomic-scale ordered sp3-carbon nanothread (CNTh) upon compression. With the help of perfectly aligned π-π stacked molecules and strong intermolecular hydrogen bonds, crystalline poly-FDCA CNTh with uniform syn-configuration was obtained above 11 GPa, with the crystal structure determined by Rietveld refinement of the X-ray diffraction (XRD). The in situ XRD and theoretical simulation results show that the FDCA experienced continuous [4 + 2] Diels-Alder reactions along the stacking direction at the threshold C···C distance of ∼2.8 Å. Benefiting from the abundant carbonyl groups, the poly-FDCA shows a high specific capacity of 375 mAh g-1 as an anode material of a lithium battery with excellent Coulombic efficiency and rate performance. This is the first time a three-dimensional crystalline CNTh is obtained, and we demonstrated it is the hydrogen bonds that lead to the formation of the crystalline material with a unique configuration. It also provides a new method to move biomass compounds toward advanced functional carbon materials.

Exploring frictional performance of diamond nanothread reinforced polymer composites from the atomistic simulation and density functional theory

Diamond nanothread (DNT), which has been recently found to outperform other conventional carbon-based nanomaterials, is a promising reinforcer for polymer composites. Here, we find that DNT can significantly improve the frictional resistance of polymethyl methacrylate (PMMA) composites via atomistic simulations and density functional theory (DFT) calculations. Results show that the friction coefficient of PMMA composite is reduced by 25.98% with the incorporation of DNT due to the excellent interfacial interactions including vdW interaction and mechanical interlocking. These lead to reduced cohesive energy at the Fe-PMMA interface and lower polymer mobility. The improvement of frictional resistance is more significant by nitrogen-doped DNT (by 43.72%) due to the rougher landscape of molecular electronic potential and larger binding energy, resulting in better interfacial interactions. Besides, it is found that the improvement of frictional resistance by DNT is less significant at elevated temperatures. The degrading mechanisms are attributed to the generation of free volume at the DNT-PMMA interface, which decreases the interfacial shear strength and weakens the interfacial interactions. These findings could make advances towards the understanding of physical mechanisms governing the frictional properties of polymer composites, and provides useful guidance for the design of advanced polymer composites with good service life.

Thermal stability and melting mechanism of diamond nanothreads: Insight from molecular dynamics simulation

In recent years, diamond nanothreads (DNTs) have attracted a wide attention of many experimental and theoretical studies. DNTs are composed of carbon polygons such as 5-, 6-, 7-, and 8-membered carbon rings. In this study, via molecular dynamics simulation we have studied the thermal stability and melting process of 15 lowest-energy DNTs into three classes; achiral, stiff-chiral, and soft-chiral, respectively. The achiral, stiff-chiral, and soft-chiral classes consist of 6, 4, and 5 molecular models, respectively. The results showed that DNTs have different melting points due to the various morphologies and different arrangements of carbon rings. Also, results showed that DNTs composed of purely 6-membered carbon rings have high thermal stability and melting point, wheras DNTs with dissimilar and distorted carbon polygons have lower melting point. In addition, the results showed that DNTs with Stone-Wales defects (SW) have lower thermal stability and melting point. Moreover, the results showed that the achiral, stiff-chiral, and soft-chiral DNTs have the same melting mechanism. During melting process, the increasing sp3 C-C bonds length and their dissociation occurs as the themperature increases. The broken bonds resulting in the formation of larger sp2-carbon rings. The higher temperatures lead to the dissociation of formed large rings and the formation of polyethylene-like molecular chains. Finally, at the melting point or after the melting point, these chains dissociate and the DNTs break down. In this study, the melting point of nanoparticles supported on 15 DNT substrates was also investigated via molecular dynamics simulation. The results showed that all DNTs increase the thermal stability and melting point of the nanoparticles. The role of DNTs in increasing the melting point obey the following trend: soft-chiarl > achiral > stiff-chiral. Soft-chiarl-DNTs with their helical morphologies show lowest deformation in the nanoparticle structure during the melting process.

Diamond nanothreads built of small aromatic molecules

Diamond nanothreads are a new type of low-dimensional sp3-bonded carbon nanostructure combining high strength, flexibility, and resilience. In this preview, we highlight a recent example of diamond nanothreads with long-range intrathread order based on reaction selectivity and stacking order of the reactant molecules. Diamond nanothreads are a new type of low-dimensional sp3-bonded carbon nanostructure combining high strength, flexibility, and resilience. In this preview, we highlight a recent example of diamond nanothreads with long-range intrathread order based on reaction selectivity and stacking order of the reactant molecules.

Mechanistic insights into the pressure-induced polymerization of aryl/perfluoroaryl co-crystals

The pressure-induced polymerization of aryl/perfluoroaryl co-crystals offers a strategic route to obtain sequence-defined polymeric architectures, such as diamond nanothreads, that feature a stiff sp3 hybridized backbone.

Vibration Control of Diamond Nanothreads by Lattice Defect Introduction for Application in Nanomechanical Sensors.

Carbon nanomaterials, such as carbon nanotubes (CNTs) and graphene sheets (GSs), have been adopted as resonators in vibration-based nanomechanical sensors because of their extremely high stiffness and small size. Diamond nanothreads (DNTs) are a new class of one-dimensional carbon nanomaterials with extraordinary physical and chemical properties. Their structures are similar to that of diamond in that they possess -bonds formed by a covalent interaction between multiple benzene molecules. In this study, we focus on investigating the mechanical properties and vibration behaviors of DNTs with and without lattice defects and examine the influence of density and configuration of lattice defects on the two them in detail, using the molecular dynamics method and a continuum mechanics approach. We find that Young’s modulus and the natural frequency can be controlled by alternating the density of the lattice defects. Furthermore, we investigate and explore the use of DNTs as resonators in nanosensors. It is shown that applying an additional extremely small mass or strain to all types of DNTs significantly changes their resonance frequencies. The results show that, similar to CNTs and GSs, DNTs have potential application as resonators in nano-mass and nano-strain sensors. In particular, the vibration behaviors of DNT resonators can be controlled by alternating the density of the lattice defects to achieve the best sensitivities.

Tensile mechanical characteristics of ultra-thin carbon sulfur nanothreads in orientational order

Carbon sulfur nanothreads (CSNTs) mainly composed of two chiral long alkane chains have been recently fabricated from thiophene by a pressure-induced phase transition in low-temperature, but their mechanical properties remain unexplored. Here, the critical roles of morphology and temperature on the tensile characteristics of CSNTs are for the first time examined using molecular dynamic simulations with a first-principles-based ReaxFF forcefield. It is revealed that CSNTs exhibit high tensile Young's modulus, high tensile strength and excellent ductility, and their tensile properties are morphology and temperature dependent. Morphologically, atomic arrangement with various configurations makes every CSNTs possess unique mechanical properties. Thermally, as temperature varies from 1 to 1500 K, CSNTs become mechanically weakened. In comparison with conventional diamond nanothreads (DNTs) and carbon nitride nanothreads (CNNTs), CSNTs show distinct axial elongation mechanisms, with relatively insignificant changes in chemical bond orders and bond length in the skeleton prior to the final rupture. Instead, the stretching of bond angle and dihedral angle mainly contribute to the global axial elongation, while the torsional deformation is limited due to their perfect global symmetry in the configuration. This study provides fundamental insights into the mechanics of ultra-thin CSNT structures.

Vibration Characteristics of Diamond Nanothreads Controlled by Lattice Defects Aimed at Application to Nanoscale Mass Sensors

Vibration Characteristics of Diamond Nanothreads Controlled by Lattice Defects Aimed at Application to Nanoscale Mass Sensors

Effects of 3d-transition metal doping on the electronic and magnetic properties of one-dimensional diamond nanothread**Project supported by the National Natural Science Foundation of China (Grant Nos. 21673296 and 11664038) and the Natural Science Foundation of Xinjiang Uygur Autonomous Region of China (Grant No. 2019D01C038).

The diamond nanothread (DNT), a new one-dimensional (1D) full carbon sp3 structure that has been successfully synthesized recently, has attracted widespread attention in the carbon community. By using the first-principles calculation method of density functional theory (DFT), we have studied the effects of 3d transition metal (TM) atomic doping on the electronic and magnetic properties of DNT. The results show that the spin-polarized semiconductor characteristics are achieved by doping Sc, V, Cr, Mn, and Co atoms in the DNT system. The magnetic moment ranges from 1.00 μB to 3.00 μB and the band gap value is from 0.35 eV to 2.54 eV. The Fe-doped DNT system exhibits spin-metallic state with a magnetic moment of 2.58 μB, while the Ti and Ni-doped DNT systems are nonmagnetic semiconductors. These results indicate that the 3d TM atoms doping can modulate the electronic and magnetic properties of 1D-DNT effectively, and the TM-doped DNT systems have potential applications in the fields of electronics, optoelectronics, and spintronics.

First-principles study on the effects of doping and adsorption on the electronic and magnetic properties of diamond nanothreads

Abstract Diamond nanomaterial is a one-dimensional, fully sp3 bonded carbon allotropes that has been successfully synthesized in recent years and has attracted wide attentions in the family of carbon. We used the first-principles calculation method of density functional theory to study the electronic and magnetic properties of diamond nanothreads (DNTs) from two aspects: doping and adsorption. The pristine DNTs have been substitute doped with mass atom Al(Ga). Our results show that the energy gap of the DNT system is decreased due to the presence of impurity states, when a hydrogen is adsorbed on the Al or Ga atom, the system becomes more stable and exhibit spin splitting. Al-doped DNT system is more stable than the Ga-doped one. Moreover, the result of the adsorption energy polar molecules (CO, NO) show that the adsorption of NO is more stable than that of CO, And the adsorptions of CO and NO molecules in the doped DNTs results in different electronic and magnetic properties of DNTs. These results would provide a basis for DNT in the fields of electronics and spintronics.

Atomistic Insights into the Tunable Transition from Cavitation to Crazing in Diamond Nanothread-Reinforced Polymer Composites.

Cavitation and crazing in thermosetting polymers can be sophisticatedly designed for valuable applications in optics, electronics, and biotechnology. It is a great challenge for numerical study to describe the formations of cavity and fibrils in polymer composite due to the complicated interfacial interaction. To explore this challenging task, we exploit a two-phase coarse-grained framework which serves as an efficient atomistic level-consistent approach to expose and predict the transition between cavitation and crazing in a polymeric system. The coarse-grained framework is utilized to transmit the information between single phase and interface in polymer composite, and the learning tasks of force field are fulfilled through parameterization of mechanical performances and structural characterizations. We elaborate on the intrinsic characteristics of the cavitation-crazing transition in diamond nanothread- (DNT-) reinforced polymethyl methacrylate composites, in which DNT plays a specific role of nanomodulator to tune the cavity volume ratio. The transition from cavitation to crazing can be induced through a novel dissipative mechanism of opening an interlocked network, in which case the DNT is stretched to the aligned fibrils and links crazing tightly by interfacial adhesion. The designed computational framework can broaden the scope of theoretical tools for providing better insights into the microstructure design of polymer composites.

Diamond nanothread reinforced polymer composites: Ultra-high glass transition temperature and low density

Diamond nanothread (DNT), a novel carbon-based nanomaterial exhibiting ultra-light density and outstanding mechanical properties, has attracted intensive attentions in polymer composites. This study investigates the influences of DNT on the glass transition temperature (Tg) of poly (methyl methacrylate) (PMMA) composites and reveals the glass-rubber transition mechanism through molecular dynamics simulation. We demonstrates that DNT exhibits better improvement than other carbon-based nanomaterials in enhancing the Tg of PMMA composite, suggesting that DNT is a promising reinforcement for polymer nanocomposite with higher service temperature and better mechanical performances. Significantly, we find that interfacial interactions including van der Waals interaction and mechanical interlocking play an important part in glass transition of PMMA composite. The transition from glassy state to rubbery is induced through the interfacial debonding brought by the enlargement of free volume at the interface. According to the interfacial degrading mechanism, cross links between DNT reinforcement and PMMA chains are introduced to provide bidirectional hindrance for free motions of polymer chains, resulting in a 70 K enhancement of Tg of PMMA composites. These findings not only shed light to the prospective application of DNT in advanced nanocomposite, but also provide important guidance to improve the reinforcing efficiency of nanomaterials in engineering application, such as building and aerospace industry.

Diamond nanothreads as novel nanofillers for cross-linked epoxy nanocomposites

The recently synthesized novel 1D diamond nanothreads (DNTs) have been reported to possess excellent mechanical property and may act as extraordinary new reinforcements for polymer-matrix nanocomposites. By performing a series of molecular dynamics simulations of cross-linked epoxy nanocomposites, the presence of DNTs are found to provide a remarkable improvement in the mechanical property of DNTs/epoxy nanocomposites, yielding an increase of ∼33% in tensile modulus compared with neat epoxy resin. Interestingly, a moderate aggregation of DNTs enables better enhancement in the tensile modulus, which contradicts to common notion that aggregation of nanofillers usually causes a severe deterioration on the mechanical property of nanocomposites. This encouraging reinforcing mechanism mainly stems from two aspects: 1) aggregated DNTs cause a less deterioration to the tensile modulus of cross-linked epoxy network than uniformly dispersed DNTs, and 2) aggregated DNTs enable a higher reinforcing efficiency along the loading direction owing to their straight structure arising from their relatively high bending rigidity. Moreover, the mechanical property of DNTs/epoxy nanocomposites can be further enhanced through the DNTs' functionalization because of improved load transfer capability across DNT/matrix interface. Our results suggest that DNTs are truly attractive reinforcement and may provide valuable design guidelines for high performance nanocomposites applications.

Strain engineering for thermal conductivity of diamond nanothread forests

Thermal properties of the diamond nanothread (DNT) forest array are studied using non-equilibrium molecular dynamics simulations. We find a strong anisotropic thermal property in this structure, i.e. the thermal conductivity in thread direction is over 300 times of that in the perpendicular direction. When subject to external strain, the thermal conductivity of the DNT forest decreases with increasing compressive/tensile strain in the thread direction, while thermal conductivity increases exponentially with increasing compressive strain in the perpendicular direction. The increase in thermal conductivity is attributed to the enhanced interactions among DNTs induced by compression. These results are explained by phonon spectra and structural deformation. Our findings show that diamond nanothread forest has a great potential application in the super-capacitors.

Diamond nanothread-based 2D and 3D materials: Diamond nanomeshes and nanofoams

Diamond nanothreads (DNTs) are one-dimensional, fully sp3-bonded carbon nanostructures resulting of covalent bonding between stacked benzene molecules in a crystal, induced by application of high pressure, as demonstrated in experiments. In this work, we used classical Molecular Dynamics simulations to propose the synthesis of analogous two- and three-dimensional porous nanostructures, which we named diamond nanomeshes (DNM) and diamond nanofoams (DNF), consistently to the definition of DNTs, and computed some of their structural and mechanical properties. Two different approaches toward creation of such materials are proposed. One of them consists in interconnecting finite domains of conventional DNTs, achieved through partial surface dehydrogenation and subsequent C-C covalent bonding. The other approach considers that the formation of sp3 C-C bonds between stacked benzene molecules under high pressure could be extended to polycyclic aromatic hydrocarbon (PAH) molecules, generating crosslinked DNT-like structures. Different atomic configurations can be achieved by varying the morphology of DNTs used in their construction, the PAH molecules, and the nature of the DNT covalent interconnections. The resulting materials exhibit an interesting combination of mechanical strength, flexibility, lightness, high porosity and high specific surface area, enabling potential applications in reinforced nanocomposites, gas storage/separation, sensors, among others.