Hexagonal Microstructures Research Articles

A soft bioinspired suction cup with tunable adhesion force using shape memory alloy

Abstract Suction cups has been widely utilized to grasp objects, but they typically encounter challenges with sealing failure and non-adjustable adhesion force. In this study, a bioinspired suction cup integrated with an shape memory alloy actuated module was proposed to solve these problems. The actuating performance under different input current was firstly investigated to ensure the effectiveness of the module. Then, inspired by the surface structures of the tree frog’s toe pad, the synthetic bioinspired suction cups with hexagonal microstructures at the rims were designed. The regular cup with soft and smooth rim was also fabricated for comparison study. Furthermore, the adhesion performance and surface adaptability of different two cups were studied in both dry and water conditions on substrates with various roughness levels. The results indicated that the proposed active bioinspired suction cup exhibited higher pull-off strength and better sealing on less rough substrates. The proposed bioinspired suction cup possessed the advantages of compactness and lightweight, thus demonstrating potential for integration into arrayed suction grippers.

A Single-Component Janus Zwitterionic Hydrogel Patch with a Bionic Microstructure for Postoperative Adhesion Prevention.

The development of anti-adhesion hydrogels for preventing postoperative adhesions is an ongoing challenge, particularly in achieving a balance between exceptional antifouling properties and effective in situ tissue retention. In this study, we propose a unique approach with the design of a single-component Janus zwitterionic hydrogel patch featuring a bionic microstructure. The Janus patches were prepared through free radical polymerization of sulfobetaine methacrylate with N, N'-methylenebis(2-propenamide) as the cross-linker. The incorporation of hexagonal facets separated by interconnecting grooves on one side imparts durable and reliable in situ retention capabilities to the Janus hydrogel patch when it is applied to traumatized tissues. The opposing flat surface exhibits outstanding resistance to bacteria, proteins, and cell adhesion, due to the superhydrophilicity and excellent antifouling characteristics of zwitterionic polymers. This dual functionality empowers the Janus hydrogel patch to mitigate adhesions between traumatized and surrounding tissues. The hexagonal and groove bionic microstructures facilitate rapid drainage, promoting swift contact with the tissue for increased adhesion strength, while independent hexagonal microfacets enhance the peeling energy. In an in vivo setting, Janus zwitterionic hydrogel patches with surface microstructures form mutually embedded structures with the cecum surface, minimizing the likelihood of slippage and detachment. Remarkably, in vivo experiments involving abdominal wall cecum injuries illustrate the Janus zwitterionic hydrogel patch's superior anti-adhesion effectiveness compared to commercial controls. Thus, the Janus hydrogel patch, distinguished by its bionic microstructure surface, presents substantial potential in the biomedical field for averting postoperative adhesions.

Anisotropic physics-regularized interpretable machine learning of microstructure evolution

Anisotropic Physics-Regularized Interpretable Machine Learning Microstructure Evolution (APRIMME) is a general-purpose machine learning solution for grain growth simulations. In prior work, PRIMME employed a deep neural network to predict site-specific migration as a function of its neighboring sites to model normal, isotropic, grain growth behavior. This work aims to extend this method by incorporating grain boundary misorientation-based grain growth behavior. APRIMME is trained on anisotropic simulations created using the Monte Carlo-Potts (MCP) model. The results of this work are compared statistically using grain radius, number of sides per grain, mean neighborhood misorientations, and the standard deviation of triple junction dihedral angles, and are found to match in most cases. The exceptions are small and seem to be related to two causes: (1) the deterministic model of APRIMME is learning from the stochastic simulations of MCP, which seems to accentuate triple junction behaviors; and, (2) a bias against very small grains is made evident in a quicker decrease in grains than expected at the beginning of an APRIMME simulation. APRIMME is also evaluated for its general ability to capture anisotropic grain growth behavior by first investigating different test case initial conditions, including a circle grain, three grain, and hexagonal grain microstructures.

Influence of 3D printed surface micro-structures on molding performance and dental bonding properties of zirconia

ObjectivesTo investigate the influence of the 3D printed micro-structured surfaces on the bond strength of zirconia to resin cement. MethodsZirconia specimens were divided into five groups based on manufacturing technique and surface preparation: (1) milled zirconia (M group); (2) milled zirconia airborne abraded (MA group); (3) printed zirconia (M group); (4) printed zirconia airborne abraded (PA group); and (5) printed zirconia with micro-structured surface (PM group). The surface morphology, cross-sectional morphology, and elemental composition were observed using a scanning electron microscope (SEM). Surface roughness was measured using a laser scanning confocal microscope (SLCM). Shear bond strength (SBS) was measured using a universal testing machine after bonding resin cement (n = 10). The failure modes of the bonded fracture interfaces were observed and counted using a stereomicroscope and a SEM. In addition, boundary dimensional accuracy (n = 10) and micro-structural dimensional accuracy (n = 20) of printed zirconia specimens with micro-structured surfaces were measured using digital calipers and Fiji software. The crystalline phase changes before and after surface treatment were investigated using X-ray diffractometry. Data was analysed using one-way ANOVA and Tukey HSD post-hoc tests (α = 0.05). ResultThe surface micro-structures of the PM group had regular morphology and no obvious defects. The surface roughness results showed that the PM group had higher Sa (42.21±1.38 um) and Ra (21.25±1.80 um) values than the other four groups (p < 0.001). The SBS test showed that the bond strength of the PM group reached 11.23 ± 0.66 MPa, which was 55.97% (p < 0.001) higher than that of the P group (7.20 ± 1.14 MPa). The boundary dimensional accuracy of the PM group was proficient (diameter: 99.63 ± 0.31%, thickness: 98.05 ± 1.12%), and the actual fabrication dimensions of the hexagonal micro-structures reached 77.45%-80.01% of the original design. The micro-structured surface did not affect the crystalline phase of zirconia. ConclusionsThe current study illustrates that 3D-printed microstructured surfaces effectively improve the bond strength of zirconia to resin cements. Clinical significanceWith the advantage of 3D printing, this study provides a new idea for improving the bonding properties of zirconia.

Experimental Study and Neural Network Model to Predict Formability of Magnesium Alloy AZ31B

Magnesium alloy is an emerging smart metal used in various industries like automotive and aerospace industry, due to their lightweight and excellent strength-to-weight ratio. Formability, a critical factor in manufacturing processes, determines the alloy’s ability to undergo deformation without fracture or defects. Fuel economy and environmental conservatives are the key desirable factors in selection of magnesium alloy sheets. Magnesium alloy sheets have low formability at room temperature due to their hexagonal closed-packed microstructures. As the magnesium’s formability at room temperature is considerably low, stretch forming tests are conducted at moderate temperatures. For this purpose, commercially available AZ31B magnesium alloy sheet of 1.1mm thickness has been used and tested at room temperature, 25 degree to within medium temperatures range and at a higher strain rate of 0.01/s. The main objective of an experimental study to predict the formability of magnesium alloy sheets is to gather data through controlled tests and measurements. This data and Forming Limit Diagram (FLD) can be used to analyse the formability of material, it defines failure criteria. On the other hand, using a neural network to predict formability involves training the network on the collected experimental data. Once trained, the neural network can predict the formability of new magnesium alloy sheets based on their characteristics, offering a faster and potentially more accurate prediction method compared to traditional models. This work explores into the realm of regression modelling utilizing neural networks, a powerful subset of machine learning techniques. It begins with a discussion on the setup of machine learning models, emphasizing the crucial steps involved in data preprocessing, model selection, and evaluation.

A superamphiphobic surface with ordered hexagonal microstructures inspired by springtails

Inspired by springtails, we prepared an ordered hexagonal microscale and nanoparticle composite superamphiphobic surface, which can repel liquids with different surface tensions.

Fine-layered CP-Ti /Ti–6Al–4V composites by laser powder bed fusion

This work aimed to provide new insights into the manufacturing of a composite material composed of alternating micrometric layers of CP-Ti and Ti–6Al–4V, which was achieved using a modified laser powder bed fusion platform. Dense materials were obtained, and interface analysis revealed the formation of a solid solution intermixed region. Both CP-Ti and Ti–6Al–4V layers exhibited a hexagonal martensitic microstructure. Texture preservation between layers was observed, and it was attributed to epitaxy during the solidification process. The multi-layered material exhibited increased strength with higher volume fractions of Ti–6Al–4V. The composite materials exhibited a compressive yield strength ranging from 670 to 930 MPa, values that did not follow the simple rule of mixtures.

3D Printed Magneto-Active Microfiber Scaffolds for Remote Stimulation and Guided Organization of 3D In Vitro Skeletal Muscle Models.

This work reports the rational design and fabrication of magneto-active microfiber meshes with controlled hexagonal microstructures via melt electrowriting (MEW) of a magnetized polycaprolactone-based composite. In situ iron oxide nanoparticle deposition on oxidized graphene yields homogeneously dispersed magnetic particles with sizes above 0.5µm and low aspect ratio, preventing cellular internalization and toxicity. With these fillers, homogeneous magnetic composites with high magnetic content (up to 20weight %) are obtained and processed in a solvent-free manner for the first time. MEW of magnetic composites enabled the creation of skeletal muscle-inspired design of hexagonal scaffolds with tunable fiber diameter, reconfigurable modularity, and zonal distribution of magneto-active and nonactive material, with elastic tensile deformability. External magnetic fields below 300mT are sufficient to trigger out-of-plane reversible deformation. In vitro culture of C2C12 myoblasts on three-dimensional (3D) Matrigel/collagen/MEW scaffolds showed that microfibers guided the formation of 3D myotube architectures, and the presence of magnetic particles does not significantly affect viability or differentiation rates after 8 days. Centimeter-sized skeletal muscle constructs allowed for reversible, continued, and dynamic magneto-mechanical stimulation. Overall, these innovative microfiber scaffolds provide magnetically deformable platforms suitable for dynamic culture of skeletal muscle, offering potential for in vitro disease modeling.

An adjuvant that increases the adhesion of pesticides on plant surfaces and improves the efficiency of pest control: Polyethylene glycol sol-gel polymer

Pesticides play an indispensable role in agricultural production; however, conventional pesticides generally suffer from a low foliar deposition rate and poor adhesion, resulting in the actual effective dosage reaching the target pests and diseases being <0.1%. In this study, a sol-gel synthesized from polyethylene glycol as a precursor was added to an emulsifiable concentrate, and the polyhydroxy property of the sol-gel was used as an intermediate to load the pesticide to bind onto the cuticle of crop leaves to enhance its adhesion and penetration on the crop foliage. The results showed that the emulsifiable concentrate after the addition of sol-gel had a more compact structure with a regular hexagonal microstructure, that the contact angle with the leaves was reduced by 5.6–7 at different concentrations, that the adhesion performance of pesticides was increased by 26%, that the residual amount on the leaves within 72 h was significantly increased, and that the larvae of pests died at a faster rate, with a 40% increase in mortality. Therefore, sol-gel has great potential for application in improving pesticide utilization and pest control.

Bimetallic Co3V2O8 microstructure: A versatile bifunctional electrode for supercapacitor and electrocatalysis applications

Our research focuses on hydrothermally synthesizing a bimetallic cobalt vanadium oxide Co3V2O8 (CVO) microstructure, tailoring it for use in both bifunctional supercapacitor and electrolysis applications. We carefully optimized the molar ratio of Co and V to achieve a hexagonal microstructure for Co3V2O8, confirming it through field emission scanning electron microscopy (FESEM) and High resolution transmission electron microscopy (HRTEM) studies. The optimized electrode exhibited exceptional electrochemical characteristics when utilized in a supercapacitor application. It demonstrated a superior areal capacitance of 3.76 F/cm2 at a current density of 1 mA/cm2. Subsequently, we utilized the optimized electrode in an asymmetric supercapacitor configuration with activated carbon (AC), resulting in an areal capacitance of 126.1 mF/cm2 and an energy density of 29.6 mWh/cm2 at a power density of 2.6 W/cm2. To assess the stability of this configuration, we conducted 5000 cycles at 5 mA/cm2 and observed a retention rate of 87%. Additionally, we investigated the effectiveness of the optimized electrode as an electrocatalyst for water oxidation in a 1 M KOH electrolyte. In this setup, the CVO-4 electrode exhibited a lower overpotential of 226 mV for the hydrogen evolution reaction (HER) and a Tafel slope of 178 mV/dec for HER. Overall, our findings indicate that the as-prepared optimized electrode operates highly efficiently in bifunctional applications, positioning it as a promising candidate for energy conversion and storage operations.

Could effective fracture toughness of polycrystalline aggregates exceed inner grain fracture toughness by adjusting toughness of grain boundary?

Obtaining intergranular and transgranular fractures through grain boundary engineering has been considered an efficient technique that improves the effective fracture toughness of polycrystalline aggregates. In this paper, the idealized hexagonal microstructure, random microstructures, and microstructures of grains with large aspect ratios are analyzed through a semi-analytical approach and the cohesive finite element method. The results indicate that when the aspect ratio of grains is not too large, the crack paths consisting of intergranular and transgranular fractures are approximately Mode I fracture morphologies among these microstructures. As the ratio of toughness between grain boundaries and grains varies, the effective fracture toughness of the microstructure can be increased more than the grain boundary fracture toughness but cannot exceed the inner grain fracture toughness.In contrast, the microstructure of grains with a large aspect ratio leads to deflected crack paths that are unexpectedly obtained, which implies that the approximate Mode-I intergranular fracture along transverse direction is almost impossible. The results demonstrate that the projected energy dissipation rate along the direction perpendicular to the loading axis can be significantly improved beyond the inner grain fracture toughness by enlarging the aspect ratio of the grains. Nevertheless, the mixed-mode effective fracture toughness is still limited to the grain fracture toughness. Corresponding experiments are also carried out to qualitatively verify the numerical results. The underlying mechanism for this deflection of fracture path is due to the strong anisotropy of fracture toughness. The higher the grain aspect ratio, the greater the anisotropy of the macroscopic effective fracture toughness. The energy favored fracture path is determined by the largest ratio between the driving force and the toughness of fracture over all directions. Therefore, cracks cannot propagate in the direction of the maximum fracture toughness when the aspect ratio of the grain is sufficiently large. The fracture diagrams that vary with the aspect ratio of grain and the ratio of fracture toughness between the grain and grain boundary are provided. The results can provide valuable guidance for designing microstructures and improving fracture toughness in materials.

A novel method for creation of complex microstructure cells through artificial molecular dynamics simulations

Composites have a spectrum of mechanical behavior resulting from uncertainty and variation in the microstructure shape and position. With microstructural simulation of fiber architectures, complex numerical algorithms are needed to enforce boundary constraints such as fiber-to-fiber overlap or periodic boundary conditions. Variations are not typically modeled because randomization of unique aggregate shapes can be challenging and current methods for doing so do not achieve high fiber volume fraction (FVF) when packing; however, this can cause inaccurate predictions in simulations. To address this challenge, a novel approach is developed using Molecular Dynamics (MD), achieving high FVFs up to 85% with rapid speed, easy user implementation, and a potential for capturing non-uniform fiber geometry. Two types of packing are presented to demonstrate the scope of possibilities with this approach: a post randomization molecular dynamics (PRMD) method for uniform fibers, and a mixed aggregate randomization using varying radii circles. Comparisons between periodic hexagonal, randomized, and variable radii packing fiber microstructures are performed to determine the significance of randomization and non-uniform aggregate shape for mechanical property homogenization and damage prediction in a unidirectional laminate. It was found that homogenization between the three microstructures do not vary from randomization; however, using the molecular dynamics approach randomizing fiber position and aggregate shape resulted in significant differences in predicting the transverse damage initiation, reducing the error by approximately 25% from the periodic method.

Dynamic Characterization of Hexagonal Microstructured Materials with Voids from Discrete and Continuum Models.

The mechanical response of materials such as fiber and particle composites, rocks, concrete, and granular materials, can be profoundly influenced by the existence of voids. The aim of the present work is to study the dynamic behavior of hexagonal microstructured composites with voids by using a discrete model and homogenizing materials, such as micropolar and classical Cauchy continua. Three kinds of hexagonal microstructures, named regular, hourglass, and skew, are considered with different length scales. The analysis of free vibration of a panel described as a discrete system, as a classical and as a micropolar continuum, and the comparison of results in terms of natural frequencies and modes show the advantage of the micropolar continuum in describing dynamic characteristics of orthotropic composites (i.e., regular and hourglass microstructures) with respect to the Cauchy continuum, which gives a higher error in frequency evaluations for all three hexagonal microstructured materials. Moreover, the micropolar model also satisfactorily predicts the behavior of skewed microstructured composites. Another advantage shown here by the micropolar continuum is that, like the discrete model, this continuum is able to present the scale effect of microstructures, while maintaining all the advantages of the field description. The effect of void size is also investigated and the results show that the first six frequencies of the current problem decrease by increasing in void size.

Kinetic and isotherms modeling of methyl orange and chromium (VI) onto hexagonal ZnO microstructures as a membrane for environmental remediation of wastewater

Globally, contamination of water by dyes and heavy metals (HMs) is a serious environmental and public health problem due to their carcinogenic and mutagenic nature. It is incumbent to treat innocuously before discharge. It is the first time, hexagonal zinc oxide (ZnO) microstructure are being employeed as a membrane in the simultaneous removal of methyl orange (MO) and chromium (Cr (VI)) from the aqueous solution. The surface chemistry of hexagonal ZnO was characterized for morphology, surface functional groups, crystalline nature, and elemental composition by scanning electron microscope (SEM), Fourier transmission infrared spectroscopy (FTIR), X-ray diffraction (XRD) and energy dispersive X-ray spectroscopy (EDX). Adsorption capacity and removal efficiency was determined by the laboratory batch adsorption experiments, while nonlinear, linear kinetics and isotherm models were fitted to experimental data to investigate the adsorption process. The results exhibited that the maximum adsorption capacity (qmax) of hexagonal ZnO from the Langmuir isotherm model was 80.39 mg g−1 and 84.10 mg g−1 for MO and Cr (VI) respectively. According to the modeling findings, linear langmuir fitted to the experimental data with R2 0.967 and 0.971 for both MO and Cr (VI) which indicates monolayer physical adsorption of both pollutants has taken place. Whereas, kinetic study showed nonlinear pseudo-second order with R2 0.989 and 0.986 for MO and Cr (VI) model best fitted with the experimental data. The values of thermodynamics parameters Gibbs free energy change ΔG°, heat of enthalpy ΔH° and, heat of entropy ΔS° indicate that spontaneous, endothermic, and irreversible adsorption reactions occurred. Overall, it is concluded from our observations that hexagonal ZnO has the potential to be used as an eco-friendly, cost-effective adsorbent for simultaneous remaoval of both MO and Cr (VI) from water. Findings of the current investigation provide valuable insights for the development of an inexpensive, effective and sustainable filtration method for the treatment of MO and Cr (VI) synergistically.

Wettability and biological responses of titanium surface's biomimetic hexagonal microstructure.

In this research, an experiment was conducted on how the surface wettability and biocompatibility of staplers' titanium nails impact the healing of gastrointestinal tissue. Firstly, the bionic hexagonal structure was prepared on the surface of Ti metal by laser processing technology, and the laser textured titanium samples were observed by scanning electron microscope. Then, the liquid-solid contact angle-measuring instrument was used to characterize the wettability of titanium samples. Finally, cells were cultured on the surface of different titanium samples, CCK8 assay and qRT-PCR were carried out to investigate cell adhesion and collagen secretion on the surface of different samples. The results showed that the bionic hexagonal surface increased the surface roughness, reduced the liquid-solid contact angle, and promoted the adhesion and collagen secretion of fibroblasts. The increased wettability provided a better growth environment for cell growth. Microtexture is an important factor affecting the behavior of cells and its size parameters regulate cell gene expression, which is worthy of further study.

Fabrication of hexagonal microstructure on gallium nitride films by wet etching assisted femtosecond laser ablation

Nitride-based microstructures are highly desirable for next-generation photonic and micro-electronic technologies. However, the efficient realization of regular microstructures for gallium nitride (GaN) is still technically challenging. This paper demonstrates the formation of hexagonal microstructures on GaN films via femtosecond laser ablation and wet chemical (hot KOH) etching. The fabricated hexagonal microstructures are shown to undergo anisotropic ablation. The structures with tunable profiles and dimensions are obtained by varying the laser energy and etching time. Additionally, we demonstrate that the microstructures were formed by selectively etching away the laser-irradiated region. This work could lead to a new approach to fabricating nitride-based microstructures using wet etching-assisted ultrafast laser processing technologies.

Surface micropatterning for the formation of an in vitro functional endothelial model for cell-based biosensors

Label-free biosensing, such as with surface plasmon resonance (SPR), is a highly efficient method for monitoring the responses of living cells exposed to pharmacological agents and biochemical stimuli in vitro. Conventional cell culture protocols used in cell-based biosensing generally provide little direct control over cell morphologies and phenotypes. Surface micropatterning techniques have been exploited for the controlled immobilization and establishment of well-defined cell morphologies and phenotypes. In this article, surface adhesion micropatterns are used to control the adhesion of endothelial cells within adjacent hexagonal microstructures to promote the emergence of a well-controlled and standardized cell layer phenotype onto SPR sensor surfaces. We show that the formation of cell-cell junctions can be controlled by tuning the inter-cellular spacing in groups of 3 neighbouring cells. Fluorescence microscopy was used to confirm the formation of vascular endothelium cadherin junctions, a structural marker of a functional endothelium. In order to confirm the functionality of the proposed model, the response to thrombin, a modulator of endothelium integrity, was monitored by surface plasmon resonance imaging (SPRI). Experiments demonstrate the potential of the proposed model as a primary biological signal transducer for SPRI-based analysis, with potential applications in cell biology, pharmacology and diagnostic.

Mesoporous hexagonal nanorods of NiCo2O4 nanoparticles via hydrothermal route for supercapacitor application

Binary metal oxide with a mesoporous microstructure has been considered a potential candidate electrode material for supercapacitor. The mesoporous microstructure of binary metal oxide improves electric conductivity. A mesoporous hexagonal microstructure of NiCo2O4 nanorods has been fabricated by a chemical hydrothermal method. Mesoporous hexagonal nanorods composed of small nanoparticles with an average thickness of 412 nm are prepared with a 14-hour hydrothermal reaction time. As synthesized, mesoporous hexagonal nanorods of NiCo2O4 as an electrode material show the highest specific capacitance of 1061 F/g and 184 mF/cm2 areal capacitance. The specific energy and specific power density of the NiCo2O4 electrode are 39 WhKg−1 and 683 Wkg−1. The equivalent charge resistance (Rs) and charge transfer resistance (Rct) of the NiCo2O4 electrode are 0.70 Ω and 43 Ω respectively. The NiCo2O4 electrode had an initial capacitance retention value of 81% after 3000 cycles.

Hydrothermal synthesized delafossite CuGaO2 as an electrocatalyst for water oxidation

Hydrogen production from water splitting provides an effective method to alleviate the ever-growing global energy crisis. In this work, delafossite CuGaO2 (CGO) crystal was synthesized through hydrothermal routes with Cu(NO3)2·3H2O and Ga(NO3)3·xH2O used as reactants. The addition of cetyltrimethylammonium bromide (CTAB) was found to play an important role in modifying the morphology of CuGaO2 (CGO-CTAB). With the addition of CTAB, the morphology of CGO-CTAB samples changed from irregular flake to typical hexagonal sheet microstructure, with an average size of 1–2 μm and a thickness of around 100 nm. Furthermore, the electrocatalytic activity of CGO-CTAB crystals for oxygen evolution reaction (OER) was also studied and compared with that of CGO crystals. CGO-CTAB samples exhibited better activity than CGO. An overpotential of 391.5 mV was shown to be able to generate a current density of 10 mA/cm2. The as-prepared samples also demonstrate good stability for water oxidation and relatively fast OER kinetics with a Tafel slope of 56.4 mV/dec. This work highlights the significant role of modification of CTAB surfactants in preparing CGO related crystals, and the introduction of CTAB was found to help to improve their electrocatalytic activity for OER.Graphical abstract

Molecular dynamics studies on separation of CO2/CH4 by the ionic liquids encapsulated ZIF-8

The utilisation of ZIF-8 membrane with encapsulated ionic liquids (IL@ZIF-8 composite membrane) has been demonstrated as one of the most efficient approaches for CO 2 /CH 4 separation. However, compared to pure ZIF-8 membrane, the mechanisms behind the CO 2 /CH 4 selectivity enhancement caused by the encapsulation of ILs still remain indistinct. Here, molecular dynamics (MD) simulations have been performed to investigate the separation and diffusion of gas molecules in the IL@ZIF-8. The simulated results show that the selectivity enhancement is because the adsorbed CO 2 /CH 4 ratio has been increased when ILs are encapsulated into ZIF-8. Detailed analysis indicates that the diffusion of CO 2 /CH 4 molecules follows three different pathways of the hexagonal microstructure of IL@ZIF-8 composite, of which the route to the nearest composite cells (route I ) has the highest possibility, and gives the smallest mean diffusion displacement. Lastly, the effect of CO 2 /CH 4 ratio in the initial gas mixture has been explored, and we found that CO 2 /CH 4 selectivity is related to the concentration of CO 2 , where three regions with different slopes have been classified. The diffusion mechanisms of CO 2 /CH 4 in IL@ZIF-8 composite were investigated by MD simulations, including diffusion routes and effects of CO 2 concentration. • The diffusion mechanisms of CO 2 /CH 4 molecules in IL@ZIF-8 composite were fully investigated by MD simulations. • A route with minimum length for gas molecules diffusion has been identified based the mean diffusion displacement analysis. • MD simulation reveals a general relationship between the CO 2 /CH 4 selectivity and CO 2 concentration.