Theoretical Design of Molecular Diode Based on Thiol-and Amino-Terminated Molecules

Utilizing density functional theory(DFT)and non-equilibrium Green's function,we systematically studied the electrical transport and rectification properties of thiol-and amino-terminated molecules embedded in graphene nanoribbons.We firstly found the thiol-terminated moleculesshowbetterelectron transport properties compared to the amino-terminated,which can be attributed to the strong electronwithdrawing ability and favorable coupling effects.Secondly,the symmetrical molecules show almost symmetrical current-voltage(-V)curves and exhibit negligible rectification effects.On the other hand,the asymmetrical molecules exhibit asymmetrical I-V curves and better rectification performance.The rectification effect is closely related to molecular asymmetry degrees.For example,the rectification ratio of asymmetric N6((E)-N1-(3-aminopropyl)-but-2-ene-1,4-diamine)molecule is much smaller than the N4(5-phenylthiazole-2,4-diamine)and N5(2,6-diaminohexane-1,1,5-triol)molecules.Furthermore,we found the rectification ratio of the asymmetrical amino-terminated molecules can reach 400,while the biggest rectification ratio of the thiol-terminated molecule can only reach 45.These findings offer crucial insights for future graphene molecular electronic device design.

基于联合仿真的短纤维增强聚合物共混挤出-注塑成形全流程模拟

短纤维增强聚合物广泛应用于汽车、电子、机械等领域,共混挤出和注塑成形是其最常见的制备和成形工艺。现有共混挤出与注塑成形的模拟仿真存在材料和工艺信息孤立、产品优化协同困难的问题,难以满足聚合物产品高端化与定制化的发展需求。文中提出了一种短纤维增强聚合物共混挤出-注塑成形过程的联合仿真方法,建立共混挤出过程全区域流场计算模型,基于流场模拟实现纤维断裂和纤维长度分布模拟,在此基础上,建立考虑纤维含量的流变与压力-比容-温度(PVT)模型计算材料等效热力学参数,通过模流-结构性能求解注塑拉伸试样的纤维取向与弹性模量分布,实现共混挤出-注塑成形全流程模拟。纤维质量分数为20%,30%和40%的玻纤增强尼龙6注塑拉伸试样弹性模量实验与模拟结果相对误差分别为9.94%,8.32%和3.72%,验证了联合仿真的准确性。