Molecular dynamics simulations of the aggregation behaviour of overlapped graphene sheets in linear aliphatic hydrocarbons.pdf

1、Full Terms&Conditions of access and use can be found athttp:/ SimulationISSN:0892-7022(Print)1029-0435(Online)Journal homepage:http:/ dynamics simulations of theaggregation behaviour of overlapped graphenesheets in linear aliphatic hydrocarbonsShenghui Chen,Shuangqing Sun,Chunling Li,Charles U.Pittm

2、an Jr.,ThomasE.Lacy,Songqing Hu&Steven R.GwaltneyTo cite this article:Shenghui Chen,Shuangqing Sun,Chunling Li,Charles U.Pittman Jr.,ThomasE.Lacy,Songqing Hu&Steven R.Gwaltney(2018):Molecular dynamics simulations of theaggregation behaviour of overlapped graphene sheets in linear aliphatic hydrocarb

3、ons,MolecularSimulation,DOI:10.1080/08927022.2018.1465569To link to this article:https:/doi.org/10.1080/08927022.2018.1465569Published online:26 Apr 2018.Submit your article to this journal Article views:22View related articles View Crossmark dataMolecular SiMulation,2018https:/doi.org/10.1080/08927

4、022.2018.1465569Molecular dynamics simulations of the aggregation behaviour of overlapped graphene sheets in linear aliphatic hydrocarbonsShenghuiChena,ShuangqingSunb,ChunlingLib,Charles U.Pittman Jr.c,Thomas E.Lacyd,SongqingHub and Steven R.GwaltneycaSchool of Physics and optoelectronic engineering

5、,ludong university,Yantai,Pr china;bcollege of Science,china university of Petroleum,Qingdao,Pr china;cDepartment of chemistry,Mississippi State university,Mississippi State,MS,uSa;dDepartment of aerospace engineering,Mississippi State university,Mississippi State,MS,uSaABSTRACTMolecular dynamics si

6、mulations were used to investigate the aggregation of two partially overlapped graphene sheets in hexane,dodecane and eicosane.When partially overlapped graphene sheets are adjacent to one another,they will expel the adsorbed layers of the solvent molecules on the graphene surface,and the amount of

7、overlap will increase.When the overlapped regions of the graphene sheets are separated by solvent molecules,they cannot expel the adsorption layers between them,and so the sheets remain separated.The driving force for aggregation is the van der Waals interaction between the two graphene sheets,while

8、 the van der Waals interaction between the graphene sheets and the solvent molecules inhibits graphene aggregation.The diffusion rate of the hydrocarbon molecules with shorter chain lengths is higher.Thus,they diffuse faster during graphene aggregation,which leads to a higher rate of graphene overla

9、pping in the shorter hydrocarbons.This work provides useful insights into graphene aggregation in linear hydrocarbon solvents of varying lengths at the nanoscale.1.IntroductionSince graphene was first discovered1,composite materials filled with graphene have been widely studied due to the sig-nifica

10、nt enhancement in the mechanical,electrical and thermal properties28.However,van der Waals(vdW)attractions between graphene sheets are strong,leading to the aggregation and accumulation of graphene sheets during the preparation of composites9,10.This aggregation significantly limits the per-formance

11、 of graphene-based composites11,12.Konios et al.13 added graphene oxide(GO)and chemi-cally reduced GO(rGO)into 18 different solvents to investigate graphene dispersion.They showed that the solubility and stability of graphene greatly depended on the reduction process.The dis-persions of GO in N-meth

12、yl-2-pyrrolidone(NMP),ethylene gly-col and water were more stable(solubility was about 8.7g/mL for NMP),while after reduction,better rGO solubility occurred in 1,2-dichlorbenzene(about 9g/mL)and acetonitrile(about 8.1g/mL)13.Kim et al.14 prepared graphene/polyurethane composites using solvent blendi

13、ng,melt compounding and in situ polymerisation.The graphene dispersion in polymer matrix using solvent-based blending was better than that using melt compounding.After solvent blending,the composites provided better conductive and tensile properties and lower N2 permea-bility.Li et al.15 obtained wa

14、ter-soluble graphene sheets from graphite by controlled chemical conversion,and these graphene sheets could form stable aqueous colloids without polymeric or surfactant stabilizers.The work of Yang et al.16 showed that the aggregation of graphene platelets could be significantly weakened by carbon n

15、anotubes.Synergetic effects between these platelets and the carbon nanotubes improved epoxy composite mechan-ical properties and thermal conductivities.Graphene dispersion in water and many other solvents using surfactants,polymers and other dispersants was reviewed by Texter17.Although many experim

16、ental studies have investigated ways to reduce graphene aggregation in a host matrix,it is difficult to study the mechanisms of graphene aggregation at the atomistic level using experimental methods.Computational simulations have been applied to study graphene dispersion in a matrix.Tang et al.18 performed molecular dynamics(MD)simulations to study GO aggregation in water.Aggregation was a point-line-plane process,and five forces were involved:van der Waals attrac-tion,electrostatic interactions