Lamellar water induced quantized interlayer spacing of nanochannels walls

The nanoscale confinement is of great important for the industrial applications of molecular sieve,desalination,and also essential in bio-logical transport systems.Massive efforts have been devoted to the influence of restricted spaces on the properties of confined fluids.However,the situation of channel-wall is crucial but attracts less attention and remains unknown.To fundamentally understand the mechanism of channel-walls in nanoconfinement,we investigated the interaction between the counter-force of the liquid and interlamellar spacing of nanochannel walls by considering the effect of both spatial confinement and surface wettability.The results reveal that the nanochannel stables at only a few discrete spacing states when its confinement is within 1.4 nm.The quantized interlayer spacing is attributed to water molecules becoming laminated structures,and the stable states are corresponding to the monolayer,bilayer and trilayer water configurations,respectively.The results can potentially help to understand the characterized interlayers spacing of graphene oxide membrane in water.Our findings are hold great promise in design of ion filtration membrane and artificial water/ion channels.

Structure dependent elastic properties of supergraphene

Complete replacement of aromatic carbon bonds in graphene by carbyne chains gives rise to supergraphene whose mechanical properties are expected to depend on its structure. However, this dependence is to date unclear. In this paper, explicit expressions for the in-plane stiffness and Poisson's ratio of supergraphene are obtained using a molecular mechanics model. The theoretical results show that the in-plane stiffness of supergraphene is drastically(at least one order) smaller than that of graphene, whereas its Poisson's ratio is higher than 0.5. As the index number increases(i.e., the length of carbyne chains increases and the bond density decreases), the in-plane stiffness of supergraphene decreases while the Poisson's ratio increases. By analyzing the relation among the layer modulus, in-plane stiffness and Poisson's ratio, it is revealed that the mechanism of the faster decrease in the in-plane stiffness than the bond density is due to the increase of Poisson's ratio. These findings are useful for future applications of supergraphene in nanomechanical systems.

Unusual thermal properties of graphene origami crease:A molecular dynamics study

Graphene is a two-dimensional material that can be folded into diverse and yet interesting nanostructures like macro-scale paper origami.Folding of graphene not only makes different morphological configurations but also modifies their mechanical and thermal properties.Inspired by paper origami,herein we studied systemically the effects of creases,where sp^(2)to sp^(3)bond transformation occurs,on the thermal properties of graphene origami using molecular dynamics(MD)simulations.Our MD simulation results show that tensile strain reduces(not increases)the interfacial thermal resistance owing to the presence of the crease.This unusual phenomenon is explained by the micro-heat flux migration and stress distribution.Our findings on the graphene origami enable the design of the next-generation thermal management devices and flexible electronics with tuneable properties.

Folded graphene reinforced nanocomposites with superior strength and toughness:A molecular dynamics study

Toughness and strength are important material parameters in practical structural applications.However,it remains a great challenge to achieve high toughness and high strength simultaneously for most materials.Here,we report a folded graphene(FG)reinforced copper(Cu)nanocomposite that overcomes the long-standing conflicts between toughness and strength.Intensive molecular dynamics simulations show that the 10%pre-strain-induced four-wave-patterned FG(1.09 wt%)reinforced Cu nanocomposite exhibits simultaneous enhancement in toughness(~13.59 J/m^(2)),ductility(~32.38%),and strength(~9.52 GPa),corresponding to 38.53%,58.88%,and 2.26%increase,respectively when compared with its counterpart reinforced by pristine graphene(PG).More importantly,the mechanical properties of FG/Cu nanocomposites can be effectively tuned by changing the pre-compressive strain,wave number,and peak number of FG.The toughening and strengthening mechanisms are applicable to other metal materials reinforced by other 2 D nanomaterials,opening up a new avenue for developing tough and strong metal nanocomposites.

Tuning graphene thermal modulator by rotating

Exploring the thermal transport of graphene is significant for the application of its thermal properties.However,it is still a challenge to regulate the thermal conductivity of graphene interface.We study the interfacial thermal transport mechanism of the bilayer graphene by utilizing the molecular dynamics simulations.During the simulation,the interfacial thermal conductivity is regulated and controlled by lattice matching and tailoring.The lattice mismatched bilayer graphene model,combining the straining and torsion,can increase the interfacial thermal resistance(ITR)about 3.7 times.The variation trend of the ITR is explained by utilizing the vibrational spectra and the overlap factor.Besides,the thermal conductivity is proportional to the overlapping area.Our results show that the tailoring models can regularly control the thermal conductivity in a wide range by twisting the angle between upper and lower layers.These findings can provide a guideline for thermoelectric manage-ment and device design of thermal switch.