Materials Studio Research Articles

Visualization of Macrophase Separation and Transformation in Immiscible Polymer Blends

Visualization of Macrophase Separation and Transformation in Immiscible Polymer Blends

A Novel BiOCl Based Nanocomposite Membrane for Water Desalination.

In this study, BiOCl based nanocomposites were used as photocatalytic membranes for a simulated study on water desalination in reverse osmosis membrane systems. Through molecular dynamic simulation, the molecular structure of BiOCl, BiOCl/Ag2S and BiOCl/Bi2O3 heterojunctions were designed and their electronic properties, mechanical properties, and membrane performance for water desalination were evaluated for the first time. The molecular structure was created, and a geometry optimization task was used to optimize it. Material Studio 2019 CASTEP was used for simulation of the electronic and mechanical properties and water desalination was performed by ReaxFF software under pressures between 0 and 250 MPa. The novel BiOCl based nanocomposites showed improved electronic and mechanical properties and, most importantly, improvements in salt rejection and water permeability as compared to well-known materials such as graphene and MoS2. BiOCl and BiOCl/Ag2S had a bandgap around two, which is the ideal bandgap for semiconductor photocatalysts. A salt rejection of 98% was achieved under an applied pressure of 10 MPa. Salt rejection was higher for BiOCl/Bi2O3, while water permeability was higher for BiOCl/Ag2S. The monolayer BiOCl was unstable under pressures higher than 50 MPa, but the mechanical stability of BiOCl/Ag2S increased twofold and increased fourfold for BiOCl/Bi2O3, which is even higher than MoS2. However, between the three nanocomposites, BiOCl/Ag2S was found to be the most ideal photocatalytic nanocomposite membrane.

Experiment and modeling of hydrophobic membranes for removal of organics from aqueous solution by pervaporation

Pervaporation(PV) has the advantages of high efficiency, low consumption and cleanliness, and it is widely used in the separation of organic-water or organic-organic systems. In this paper, the separation of five azeotropic systems with different molecular weights was discussed by simulation and experiment. First, a hydrophobic and alcohol-loving PDMS/ PVDF-PTFE membranes with stable mechanical properties were prepared by scraping polydimethylsiloxane (PDMS) onto the support layer of PPTFE-PVDF membranes. The relatively better membrane preparation conditions were established by SEM, FTIR and water contact angle. Then, the dissolution and diffusion processes of five azeotropic systems were simulated by Materials Studio (MS). The simulated permselectivity of order: ethyl acetate/water > 1-butanol/water > pentanol/water > isobutanol/water > ethanol/water. Finally, corresponding to the simulation, the separation performance of PDMS/PVDF-PTFE membrane for five azeotropic systems was investigated. The order of pervaporation separation index(PSI) of five azeotropic systems in the membrane as ethyl acetate/water > 1-butanol/water > pentanol/water > isobutanol/water > ethanol/water. The experimental separation results of five azeotrope systems were consistent with the MS simulation results. It shows that the MS simulation can provide some theoretical guidance for the experiment, and realize the possibility of reducing the experimental cost and workload through cheap computer resources.

Mechanical and Antibacterial Properties of h-BN-TiO2 Nanocomposite-Modified Glass Ionomer Cement

This study investigated the mechanical properties and antibacterial properties of hexagonal boron nitride and titanium dioxide (h-BN-TiO2) nanocomposite modified traditional glass ionomer cement. The mechanism of formation of the h-BN-TiO2 nanocomposite was elucidated by conducting molecular dynamics (MD) simulations using the Material Studio (MS) software. Furthermore, synthesis of h-BN-TiO2 nanocomposite by the original growth method using hexagonal boron nitride nanosheets (h-BNNs) and titanium dioxide nanoparticles (TiO2 Nps) and characterization using TEM and AFM to determine their particle sizes, morphologies, and structures. The mechanical properties and antibacterial efficacies of the glass ionomer cement composites were analyzed based on the different mass fractions (0, 0.3, 0.7, 1.1, and 1.5 wt%) of the h-BN-TiO2 nanocomposite. The results showed when the concentration of the h-BN-TiO2 nanocomposite was 1.1 wt%, the Compressive strength (CS) and Vicker hardness (VHN) were 80.2% and 149.65% higher, respectively, compared to the glass ionomer cement without any h-BN-TiO2 nanocomposite. Also, the increase in the concentration of the h-BN-TiO2 nanocomposite led to a decrease in both the coefficient of friction (COF) and solubility, but a 93.4% increase in the antibacterial properties of the glass ionomer cement composites. The cell survival rate of each group was more than 70% after 48 h, but the difference was not statistically significant (p > 0.05). Therefore, the h-BN-TiO2 nanocomposite served as a reinforcing material for glass ionomer cement, which can be useful in clinical dentistry and provide a new strategy for improving the clinical utility of glass ionomer cement.

First principles study on optical and thermal properties of BaTiS3

Electronic, optical and thermal properties of hexagonal perovskite structure of BaTiS3, are studied, by means of the density functional theory (DFT) implemented on CASTEP, Material Studio, computer program. The data is optimized with generalized gradient approximation (GGA) and exchange correlation function called local density approximation (LDA), within the Broyden-Goldfarb-Shanno (BFGS) scheme of minimization and Koelling-Harmon relativistic treatment. Structure of BaTiS3, which we studied, crystallizes in the space group P63/mmc. Our results for structural, electronic and thermal properties of BaTiS3 are reported for the first time in comparison with experimental and other theoretical results wherever these are available. The electronic band structure reveals p-type semiconducting behavior and major contribution occurs from S-3p orbitals in Valence band and the conduction band is basically constructed from Ti-3d states. Reflectivity of BaTiS3 is also founded to be higher within visible and in ultraviolet region up to 25 eV, which indicates the potentiality of this material to be utilized as a jacket to elude solar heating. Coefficient of absorption spectra of BaTiS3 reveals the conducting nature of this material. The negative values of ε1(ω) is additionally observed,which is obvious indication of Drude like behavior seen in metals. Index of refraction is relatively higher within the infrared section and steadily lowered within the visible and ultraviolet frequency region. Analysis for conductivity also favors the photoconductivity with small photon energy. Thermo dynamical properties reported for the first time with Debye temperature of 1000 K.

Bagasse Cellulose Composite Superabsorbent Material with Double-Crosslinking Network Using Chemical Modified Nano-CaCO3 Reinforcing Strategy.

To improve the salt resistance of superabsorbent materials and the gel strength of superabsorbent materials after water absorption, a bagasse cellulose-based network structure composite superabsorbent (CAAMC) was prepared via graft copolymerization of acrylamide/acrylic acid (AM/AA) onto bagasse cellulose using silane coupling agent modified nano-CaCO3 (MNC) and N,N′-methylene bisacrylamide (MBA) as a double crosslinker. The acrylamide/acrylic acid was chemically crosslinked with modified nano-CaCO3 by C-N, and a stable double crosslinked (DC) network CAAMC was formed under the joint crosslinking of N,N′-methylene bisacrylamide and modified nano-CaCO3. Modified nano-CaCO3 plays a dual role of crosslinking agent and the filler, and the gel strength of composite superabsorbent is two times higher than that of N,N′-methylene bisacrylamide single crosslinking. The maximum absorbency of CAAMC reached 712 g/g for deionized water and 72 g/g for 0.9 wt% NaCl solution. The adsorption process of CAAMC was simulated by materials studio, and the maximum adsorption energy of amino and carboxyl groups for water molecules is −2.413 kJ/mol and −2.240 kJ/mol, respectively. According to the results of CAAMC soil water retention, a small amount of CAAMC can greatly improve the soil water retention effect.

Synthesis of Magnesium Hydroxide Using Post‐Reaction Filtrate as Ammonia Carrier and Morphology Analysis

AbstractThis study proposes an advanced technology using post‐reaction filtrate as an ammonia carrier to synthesize magnesium hydroxide (MH) with small particles, which can benefit subsequent hydrothermal modification. In this work, the limitation of ammonia gas and ammonia water methods is avoided. The impact of operating parameters including MgCl2 concentration, temperature, ammonia‐to‐magnesium molar ratio, feed rate, volume of ammonia mother liquor and aging time on the magnesium yield, particle size, and morphology of MH is studied. The temperature and ammonia‐to‐magnesium molar ratio are identified as key factors affecting magnesium yield. MH with a half‐content diameter of 1.70 µm and a morphology resembling small irregular flakes is successfully synthesized at a magnesium yield of 90.06%. The predictions of idea crystal habits are also performed using Morphology and CASTEP modules with Materials Studio Software. The (0 0 1) face can be preserved with the largest facet area because of the slowest crystal growth rate and the smallest attachment energy, which exhibits that MH crystals tend to be flakes.

In situ synthesis and interfacial bonding mechanism of SiC in MgO–SiC–C refractories

Adding SiC directly to MgO–C refractories possesses the disadvantages of low dispersion and interfacial bonding strength. Herein, the in situ synthesized SiC was introduced into the MgO–SiC–C refractories to maintain the original excellent performance of MgO–C refractories and reduce the carbon dissolution in molten steel. With the increase of Si and C content in raw materials, the morphology of SiC changed from whisker to network, whose growth mechanism was vapor–solid and vapor–liquid–solid. The network structure and uniform distribution of SiC improved the thermal shock resistance of MgO–SiC–C refractories. According to the analysis of molecular dynamics simulation by Materials Studio software, SiC strengthened the relationship between periclase and graphite to enhance the structure of the compound.

Carbazole-siloxane based polymers for the selective detection of 4-nitrophenol and Fe3+

Silicone-containing polymers have broad application prospects in the detection of many analytes due to their unique fluorescence properties. Environmental pollutants are very complex, which have prompted researchers to explore different detection methods. In this report, two kinds of polymers were synthesized via Heck-reaction between tetramethyltetravinylcyclotetrasiloxane (D4vi) and carbazole derivatives. The polymers showed excellent fluorescent properties and exhibited high sensitivity to 4-nitrophenol (4-NP) and Fe3+ in solution. Furthermore, the polymers still showed high sensitivity for Fe3+ in living cells. We estimate that the cyclic structure of D4vi and carbazole structure will serve as responsive sites for Fe3+ and 4-NP, respectively. The frontier molecular orbitals of polymers were calculated by Materials Studio and the effect of the cyclic structure of D4vi on their responsiveness had been discussed. The design idea of the polymer sensors can provide a new direction for the synthesis of multi-response polymer fluorescent probes.

Self-assembly behavior of temperature sensitive additive in polypropylene matrix: Molecular dynamics simulations

In this paper, material studio software was used to simulate the self-assembly probability of N,N’,N”-tricyclohexyl-1,3,5-benzenetricarboxylamid as a temperature-sensitive additive in molten polypropylene. 15 cells of PP were simulated based on RSM (CCD) designed, with various temperature of 200–300 °C, PP chain length of 20–300 repeat unit and additive content of 0.5–2% wt. as independent variables. Additive molecule diffusion coefficient and distance between a pair of additive molecules were considered as responses. To justify the change in molecular diffusion coefficient, the free volume of the system and polymer chain mobility were calculated for each simulated cell. It is found that temperature directly affects the diffusion coefficient of additive molecules through free volume and mobility of polymer chains, while it had little effect on the intermolecular distance. The diffusion coefficient and intermolecular distance of additive decreased by increasing additive content. A longer polymer chain with more free volume increased slightly the mobility of additive molecules, but had no effect on their distance. In general, self-assembly of additive molecules is more likely at higher temperatures and optimal additive contents. Optical microscopy observations verify the simulation results.

Molecular dynamics simulation of the adsorption properties of graphene oxide/graphene composite for alkali metal ions

As one of the effective methods to remove heavy metals, graphene (G) composite adsorption technology is irreplaceable in water pollution control and water purification, but its adsorption mechanism is not clear. Materials Studio (MS) software was used to simulate the molecular dynamics of the interaction between graphene oxide/graphene (GO/G) composite and alkali metal ion (M+). Based on the calculation of the interaction energy, diffusion coefficient and radial distribution function (RDF), The adsorption law of GO/G on M+ was investigated and its mechanism was revealed. It provides a theoretical basis for the research and development of the adsorption performance of G composite electrode. The calculated results show that the interaction energy between different M+ and GO/G is negative, indicating that the interaction between them is mutual attraction. The energy of GO/G composites and the total energy of M+-GO/G increase with the increase of M+ radius. The larger the hydrated ion radius of M+ is, the larger the diffusion coefficient is. Cs+ diffusion coefficient is slightly lower than rubidium. According to RDF analysis, M+-GO and M+ − O (GO) both have bonding within 3.5 Å and non-bonding after 3.5 Å, and the non-bonding interaction of M+-GO is greater. However, the bonding interaction between M+-O(GO) is larger than the non-bonding interaction, indicating that there are bonding and non-bonding interactions in the system when GO/G composite adsorb M+. The interaction between M+ and GO surface is mainly provided by non-bonding interaction, while the interaction between M+ and O atoms of GO surface is mainly provided by bonding interaction.

Construction of Pingdingshan coal molecular model based on FT-IR and 13C-NMR

To construct a molecular model of coal and study the adsorption characteristics from the perspective of microscopic molecules, the microstructure of coal samples from Pingdingshan mining area in China was studied by means of Fourier transform infrared spectroscopy (FT-IR) and carbon-13 nuclear magnetic resonance spectroscopy (13C-NMR). The coal mainly possesses an aromatic molecular structure with fa (aromaticity), faH and XBP (the ratio of aromatic bridge carbon to surrounding carbon) being 0.86, 0.29 and 0.54, respectively. According to the results, the aromatic structure, with a high degree of condensation, is mainly dominated by pyrene and chrysene, while the aliphatic structure is mainly composed of methyl and methylene whose ratio is about 0.52. Furthermore, it contains a small amount of oxygen-containing functional groups such as carbonyl group, phenolic hydroxyl group and ether bond. In light of the above-mentioned molecular structure characteristics, the periodic structure model of Pingdingshan coal with the molecular formula C108H71O4N was constructed based on molecular mechanics and molecular dynamics by using the Materials Studio software. The model has a density of 1.3 g/cm3, a porosity of 4.1% and a specific surface area of 614.5 m2/g, faithfully reflecting the structural information of coal sample. Moreover, methane isothermal adsorption curves were simulated by the model at the temperatures of 318, 333 and 348 K. The experimentally measured and simulated isothermal methane adsorption curves both exhibit an error of smaller than 5% under high pressure. The results verify rationality and accuracy of the model structure. The study provides a model basis for further research on coal on the microscopic level.

Radium sorption on biotite; surface complexation modeling study

The sorption of Ra on Olkiluoto biotite in the context of deep geological disposal of spent nuclear fuel was studied with isotherm batch sorption experiments. Ba was used as an analog for Ra in the experiments and modeling studies. A wide concentration range of Ra/Ba was used in the isotherm studies (2.6 × 10−9 M to 1 × 10−3 M) in addition to four different Olkiluoto reference groundwaters with salinity types ranging from fresh to saline. Experimental results show that both in the fresh and saline reference groundwaters, the distribution coefficients of Ra tend to decrease in the higher isotherm concentrations of Ba. With one reference groundwater, the distribution coefficients increased with the concentration of Ba due to significant coprecipitation of Ra. With the fresh reference groundwaters, the distribution coefficients of Ra were consistently approximately one order of magnitude lower than in the saline reference groundwater. A PHREEQC multi-site complexation model coupled with an optimization tool in Python was used to interpret the experimental Ra sorption results. Molecular modeling with CASTEP code implemented into Materials Studio was used to update the PHREEQC model with more realistic biotite sorption site density data. It was observed that while the multi-site model predicts the sorption of Ra well in lower isotherm concentrations, auxiliary reactions of Ra disrupt the model in high Ba isotherm concentrations. The experimental and modeled distribution coefficient data of Ra on biotite can be used in the safety case calculations of the deep geological disposal of spent nuclear fuel in Finland and Sweden.

A Mechanistic Study of Wettability Alteration of Calcite as an Example of Carbonate Reservoirs Using Molecular Dynamics Simulation

Abstract It is common sense the wettability alteration in carbonate reservoirs stems from the oil–rock interactions; however, the exact oil component acting as the dominant role remains unclear. This study adopts molecular dynamics technology, takes {101¯4} calcite crystal surface as the mineral surface of carbonate reservoir, uses multiple single-component oils to characterize real crude oil, and conducts research on the wettability alteration of carbonate reservoirs. First, based on the chromatographic analysis results of a certain carbonate reservoir in the Middle East, the simulated oil is divided into polar and nonpolar components. Then, the Materials Studio software and the COMPASS force field were employed to study the natural wettability of the calcite surface, as well as the adsorption characteristic of different oil components and water on the surface of calcite. Results show that the surface of calcite in carbonate reservoirs is indeed water-wet under initial conditions, and the contact angle of calcite surface is equal to 68.47 deg ± 3.6 deg. However, when the crude oil component contains groups of hydroxyl functional group, especially the strongly polar component with multiple hydroxyl functional groups, such as glycerol (GLYC), will cause the originally water-wet calcite surface becomes oil-wet. The main reason for the GLYC component altering the wettability of the calcite surface is hydrogen bonding and Coulomb interaction. Moreover, the results of centroid displacement of nine oil components shown that besides the GLYC component, the rest of the eight components, including the polar component of nitrogen-containing functional groups (Indole), sulfur-containing functional groups (Benzothiophene), as well as five nonpolar components, all migrate away from the calcite surface.

Adsorption Properties of ZSM-5 Molecular Sieve for Perfluoroisobutyronitrile Mixtures and Its Fluorocarbon Decomposition Products

Perfluoroisobutyronitrile (C4F7N), an environment-friendly insulating gas, has excellent insulating properties and has the potential to be used in gas-insulated equipment when mixed with CO2. Selecting suitable adsorption materials to adsorb the decomposition products of the C4F7N mixture can ensure the safe and stable operation of the gas-insulated equipment and the personal safety of the operators in the electric power industry. The adsorption characteristics of the ZSM-5 molecular sieve on C4F7N and its five fluorocarbon decomposition products were investigated by adsorption experiments. The results show that the ZSM-5 molecular sieve has a certain adsorption effect on six fluorocarbon gases; the adsorption performance of C3F6 and C3F8 are the best, with an adsorption efficiency over 85%, while the concentration of CO2 and C4F7N is affected by the ZSM-5 molecular sieve. At the same time, the paper based on the Metropolis Monte Carlo simulation of Materials Studio software found that the ZSM-5 molecular sieve has the strongest adsorption effect on C4F7N molecules and the weakest adsorption effect on CO2 molecules. The stronger the polarity of the gas molecule, the more obvious the adsorption effect of molecular sieve structure on it. As a result, the ZSM-5 molecular sieve could be used in tail gas purification of insulated equipment, as well as to provide solutions for the development and production of protective equipment.

Theoretical and experimental study of the photodegradation of methyl orange in the presence of different morphologies of Au-ZnO using Monte Carlo dynamic simulation.

Herein, a simple approach was formed based on synthesizing different morphologies of ZnO and Au-ZnO as photocatalyst. In this study, ZnO and Au-ZnO were synthesized via a co-precipitation method and fully characterized via scanning electron microscopy (SEM), X-ray diffraction (XRD), and energy-dispersive X-ray spectroscopy (EDX). Three different ratios of Zn2+:OH- (1:2, 1:3, and 1:5) controlled the morphology of samples, which were made into spindle, star, and flower structures, respectively. Then, the photocatalytic activity was studied and compared. Their comparison showed that the flower morphology for ZnO and Au-ZnO was more effective in photocatalytic degradation and decolorization of methyl orange dye. Also, quantum and Monte Carlo (MC) calculations were carried out to investigate the adsorption of methyl orange (MO) molecules on ZnO(111) surface in the presence of Au or without Au in aqueous conditions by Monte Carlo adsorption locator simulations in the Materials Studio 2017 software. Au created a tendency to form a relatively strong interaction of MO with the ZnO(111) surface. The adsorption of MO on Au-ZnO(111) in the presence of Au was more significant than that of MO on ZnO(111), suggesting Au could significantly improve the reactivity of the methyl orange toward the ZnO(111).

A General Synthetic Approach of Organic Lateral Heterostructures for Optical Signal Converters in All-Color Wavelength

A General Synthetic Approach of Organic Lateral Heterostructures for Optical Signal Converters in All-Color Wavelength

A combined experimental and micromechanical approach to investigating PTC and NTC effects in CNT-polypropylene composites under a self-heating condition

The present study proposed a combined experimental and micromechanical approach to investigating positive temperature coefficient (PTC) and negative temperature coefficient (NTC) effects in carbon nanotube (CNT)-polypropylene composites under a self-heating condition. The electrical and heating performance of the composites were investigated by electrical conductivity measurements and self-heating tests with various input voltages. The test results showed that composites with a CNT content of 5.0 wt.% exhibited excessive heat generation, showing a transition of the PTC effect to the NTC effect. Moreover, a micromechanical modeling was proposed to predict the occurrence of the PTC and NTC effects in the composites, considering various distances between CNTs and wavinesses of CNT. The change of the distance between CNTs under a heating condition was estimated, using the molecular dynamics software Material studio. Comparisons between the predictions and the experimental results were made to show the applicability of the proposed modeling scheme.

Synergetic removal of oppositely charged dyes by co-precipitation and amphoteric self-floating capturer: Mechanism investigation by molecular simulation

The adsorption performances of adsorbents to dyes are hard to maintain in a wide pH range because most of the reactions are pH-dependent, developing a cost-effective strategy to break the pH-limitation is significant. In this study, an amphoteric self-floating adsorbent (Am-SA) was synthesized by hollow silica microsphere surface modification, which was useful to capture anionic acid orange 7 (AO7) and cationic crystal violet (CV) dyes, but the adsorption performances were also greatly affected by pH. Fortunately, a co-precipitation phenomenon was noticed when the AO7 and CV solutions were mixed with a 1:1 molecule ratio. The precise structures of AO7 and CV molecules were constructed and the AO7-CV-H2O mixed system was structured by Materials Studio. Besides, this system was involved in a dynamic simulation to reveal the mechanism of the co-precipitation phenomenon. The simulation results showed H2O molecules dispersed out of the system via thermal motions within 30 ps, but the AO7 and CV molecules aggregated to each other via electrostatic attractions. The energy calculations also demonstrated the electrostatic attraction between AO7 and CV is the dominant factor that induced the aggregation. The aggregation phenomena were also observed in various mixed cationic–anionic dyes systems. The removals of dyes significantly improved in a wide pH range in the mixed systems as the captures of the aggregated dye clusters were much easier than that of independent dye molecules, and both co-precipitation and adsorption contributed to it. Proper utilization of the aggregation behaviors between dyes can be regarded as a prospective strategy in cost-effective treatments.

The electronic properties and water desalination performance of a photocatalytic TiO2/MoS2 nanocomposites bilayer membrane: a molecular dynamic simulation.

Due to the rapid depletion of water resources, more interest is paid for the efficient desalination process in recent years. MoS2 membrane aroused attention due to its high mechanical stability and electronic properties, which can sustain extra-large strains. In this study, the electronic properties and water desalination performance of TiO2/MoS2-hexagonal, and TiO2/MoS2-rhombohedral nanocomposites bilayer membranes were studied and simulated for the first time. The effect of TiO2 in the performance of MoS2 was observed in water desalination under the defined applied pressure ranging from 50 to 250MPa with a 6.4Å pore diameter. The membrane structure is created and optimized. The energy minimized for TiO2 from - 19,596.4282kcal/mol for the initial structure to - 19,605.1611kcal/mol for the final structure. For TiO2/MoS2-hexagonal, the energy minimized from - 4955.54271eV) to - 4955.62091eV and TiO2/MoS2-rhombohedral from - 6042.26925eV to - 6046.91835eV. A molecular dynamic (MD) simulation was performed using Material Studio 2019 to study the electronic properties under 0-1eV electric field using the CASTEP code. The results showed a better photocatalytic performance under the external electric field. The effect of external electric field significantly intensifies absorption in the visible range and achieved a high photocatalytic activity on TiO2/MoS2. TiO2, TiO2/MoS2-hexagonal and TiO2/MoS2-rhombohedral nanocomposites bilayer membranes are simulated and evaluated for the water desalination using ReaxFF software. Both MoS2 phases with TiO2 have achieved a high salt rejection up to 97% (P-value = 0.0036, R2 = 0.958), while TiO2/MoS2-rhombohedral achieved the highest permeability (6.0*10-8mmgcm-2s-1bar-1) (P-value = 0.000296, R2 = 0.972) under 250MPa applied pressure.