A Monte Carlo based scheme for the formation of graphite oxide (GO) was developed and implemented. Rosenbluth factor used to select intermediate structures in an attempt form stable, low-energy, realistic GO. The resulted production GO that has interplanar spacing 5.8 Å, good agreement with experimental value (5.97 Å). Epoxide hydroxyl functional groups dominate basal planes, a finding is consistent experiment. Individual sheets are wrinkled average root-mean-square deviation 0.33 ± 0.04 Å....

Coupled quantum mechanical/molecular mechanical (QM/MM) calculations were used to study the effects of large defects and cracks on properties carbon nanotubes graphene sheets. The semi-empirical method PM3 was treat QM subdomains a Tersoff-Brenner potential for molecular mechanics; some also done using density functional theory (DFT). Scaling so that modulus overall stress-strain behavior MM models matched quite closely essential obtaining meaningful coupled properties. numerical results...

Abstract The ability to bias chemical reaction pathways is a fundamental goal for chemists and material scientists produce innovative materials. Recently, two-dimensional materials have emerged as potential platforms exploring novel mechanically activated reactions. Here we report mechanochemical phenomenon in graphene oxide membranes, covalent epoxide-to-ether functional group transformations that deviate from epoxide ring-opening reactions, discovered through nanomechanical experiments...

Functional groups and their associated charges are responsible for the binding release of molecules from surfaces particles in nanodiamond colloids. In this work, we describe a combined set experimental computational techniques that used to characterize these functional quantitatively. The examined during study amphoteric, as one would expect made carbon, with high concentrations phenols, pyrones, sulfonic acid groups; average 50-nm-diameter aggregate has approximately 22000 7000 9000 acids....

Graphene oxide (GO), whose highly tunable surface chemistry enables the formation of strong interfacial hydrogen-bond networks, has garnered increasing interest in design devices that operate presence water. For instance, previous studies have suggested controlling GO's leads to enhancements shear strength, allowing engineers manage deformation pathways and control failure mechanisms. However, these reports not explored role ambient humidity only offer extensive chemical modifications as...

The mechanical properties of graphene oxide (GO) are great importance for applications in materials engineering. Previous mechanochemical studies GO typically focused on the influence degree oxidation behavior. In this study, using density functional-based tight binding simulations, validated functional theory we reveal that deformation and failure strongly dependent relative concentrations epoxide (−O−) hydroxyl (−OH) groups. Hydroxyl groups cause to behave as a brittle material; by...

Beam-surface scattering experiments and theoretical direct dynamics based on density functional theory calculations are used to investigate hyperthermal collisions between O((3)P) highly oriented pyrolytic graphite (HOPG). The simulations suggest that the HOPG surface becomes functionalized with epoxide groups. Intersystem crossing (ISC) lowest-energy triplet singlet potential-energy surfaces is not necessary for this functionalization occur. Both experiment indicate incoming O atoms can...

The mechanical behavior of carbon nanotube (CNT)-based fibers and nanocomposites depends intimately on the shear interactions between adjacent tubes. We have applied an experimental-computational approach to investigate CNTs within individual double-walled (DWNT) bundles. force required pull out inner bundle DWNTs from outer shell was measured using in situ scanning electron microscopy methods. normalized per CNT-CNT interaction (1.7 ± 1.0 nN) found be considerably higher than molecular...

This paper reports a method to realize crack-free graphene wrinkles with variable spatial wavelengths and switchable orientations. Graphene supported on thin fluoropolymer prestrained elastomer substrate can exhibit conformal wrinkling after strain relief. The wrinkle orientation could be switched beyond the intrinsic fracture limit of for hundreds cycles stretching releasing without forming cracks. Mechanical modeling revealed that layer mediated structural evolution crack formation or...

The chemical bonding and morphology of vapor deposited (CVD) diamond films exposed to thermal (∼0.04 eV) hyperthermal (5 7.5 atomic oxygen (AO) were studied by using high resolution electron energy loss spectroscopy (HREELS), force microscopy, theoretical simulations. Although exposure AO caused subtle changes the surface morphology, resulted in selective etching facets: (100) facets remained essentially unaffected, whereas (111)-oriented other severely etched. HREELS reveals that hydrogen...

We perform a detailed density functional theory assessment of the factors that determine shear interactions between carbon nanotubes (CNTs) within bundles and in related CNT graphene structures including yarns, providing an explanation for force measured recent experiments (Filleter, T. etal. Nano Lett. 2012, 12, 73). The potential energy barriers separating AB stacked are found to be irrelevant analysis yarns due turbostratic stacking, as result, tube-tube strength pristine CNTs is...

Understanding atomic interactions between constituents is critical to the design of high-performance nanocomposites. Here, we report an experimental-computational approach investigate adhesion energy as-produced arc discharge multiwalled carbon nanotubes (MWCNTs) and graphene. An in situ scanning electron microscope (SEM) experiment used peel MWCNTs from graphene grown on copper foils. The force during peeling obtained by monitoring deflection a cantilever. Finite element molecular mechanics...

The mechanical and thermal properties of transition metal dichalcogenides (TMDs) are directly relevant to their applications in electronics, thermoelectric devices, heat management systems. In this study, we use a machine learning (ML) approach parametrize molecular dynamics (MD) force fields predict the transport library monolayered TMDs (MoS2, MoTe2, WSe2, WS2, ReS2). ML-trained were then employed equilibrium MD simulations calculate lattice conductivities foregoing investigate how they...

Electromechanical and photonic properties of semiconducting nanowires depend on their strain states are limited by extent deformation. A fundamental understanding the mechanical response individual is therefore essential to assess system reliability define design space future nanowire-based devices. Here we perform a large-scale density functional theory (DFT) investigation failure modes in zinc oxide (ZnO) nanowires. Nanowires as large 3.6 nm diameter with 864 atoms were investigated. The...

Abstract This investigation presents a generally applicable framework for parameterizing interatomic potentials to accurately capture large deformation pathways. It incorporates multi-objective genetic algorithm, training and screening property sets, correlation principal component analyses. The enables iterative definition of properties in the guided by relationships between properties, aiming achieve optimal parametrizations interest. Specifically, performance increasingly complex...

Carbon materials have mechanical, electrical, optical, and tribological properties that make them attractive for use in a wide range of applications. Two attractive, their hardness inertness many chemical environments, also difficult to process into useful forms. The atomic oxygen other forms oxidation has become popular option processing these (etching, erosion, functionalization, etc.). This Account provides an overview the theory describe mechanisms diamond graphite using hyperthermal...

Weak interfilament van der Waals interactions are potentially a significant roadblock in the development of carbon nanotube- (CNT-) and graphene-based nanocomposites. Chemical functionalization is envisioned as means introducing stronger intermolecular at nanoscale interfaces, which turn could enhance composite strength. This paper reports measurements adhesive energy CNT-graphite interfaces functionalized with various coverages arylpropionic acid. Peeling experiments conducted situ scanning...

Hyperthermal collisions of ground-state atomic oxygen with H2O have been investigated, special attention paid to the H-atom elimination reaction, O(3P) + H2O(X 1A1) → HO2(2A') H(2S). This reaction was observed in a crossed-beams experiment, and relative excitation function region around its energy threshold (50−80 kcal mol-1) measured. Direct dynamics calculations were also performed at two levels theory, B3LYP/6-31G(d,p) MP2/6-31G(d,p). The shape B3LYP closely matches that experiment....

Nanoscale wrinkling on the surfaces of polymer-based materials can be precisely controlled by depositing thin metal films varying thicknesses. The deposition these fundamentally alters mechanical properties substrates in ways that are not simply described using traditional continuum frameworks. In particular, we find, modeling within a finite element analysis approach, very act film may alter Young's modulus polymer substrate to depths up few hundred nanometers, creating modified interfacial...

The dynamics of O((3)P) + CO(2) collisions at hyperthermal energies were investigated experimentally and theoretically. Crossed-molecular-beams experiments <E(coll)> = 98.8 kcal mol(-1) performed with isotopically labeled (12)C(18)O(2) to distinguish products nonreactive scattering from those reactive scattering. following product channels observed: elastic inelastic ((16)O((3)P) (12)C(18)O(2)), isotope exchange ((18)O (16)O(12)C(18)O), oxygen-atom abstraction ((18)O(16)O (12)C(18)O)....