Utilizing the periodically structured metal-organic framework （MOF） as the reaction vessel is a promising technique to achieve the aligned polymer molecular chains, where the diffusion procedure of the polymer monom...Utilizing the periodically structured metal-organic framework （MOF） as the reaction vessel is a promising technique to achieve the aligned polymer molecular chains, where the diffusion procedure of the polymer monomer inside MOF is one of the key mechanisms. To investigate the diffusion mechanism of fluorinated polymer monomers in MOFs, in this paper the molecular dynamics simulations combined with the density functional theory and the Monte Carlo method are used and the all-atom models of TFMA （trifluoroethyl methacrylate） monomer and two types of MOFs,[Zn2（BDC）2（TED）]n and[Zn2（BPDC）2（TED）]n, are established. The diffusion behaviors of TFMA monomer in these two MOFs are simulated and the main influencing factors are analyzed. The obtained results are as follows. First, the electrostatic interactions between TFMA monomers and MOFs cause the monomers to concentrate in the MOF channel, which slows down the monomer diffusion. Second, the anisotropic shape of the one-dimensional MOF channel leads to different diffusion speeds of monomers in different directions. Third, MOF with a larger pore diameter due to a longer organic ligand,[Zn2（BPDC）2（TED）]n in this paper, facilitates the diffusion of monomers in the MOF channel. Finally, as the number of monomers increases, the self-diffusion coefficient is reduced by the steric effect.展开更多
Self-organization in thin micro-films has shown potential for the production of microelements with specific structures and functions; however, little is known about its mechanism of formation. A 2-D molecular dynamics...Self-organization in thin micro-films has shown potential for the production of microelements with specific structures and functions; however, little is known about its mechanism of formation. A 2-D molecular dynamics (MD) simulation on this process is carried out in this paper for films between two parallel walls (substrates) under different initial conditions. The films consist of two immiscible components (A and B). The simulation results in alternative columns perpendicular to the walls, which are rich either in A or in B molecules, respectively, apparently owing to their different interactions with the walls. The characteristic breadths of the columns depend on the distance between the two walls. By providing microscopic details of the self-organization processes and the resulted structures, MD simulation proves itself as a unique way for analyzing the dynamics of thin films.展开更多
Self-healing materials have been developed over the past decade with the recovery ability after damage.However,most researches focused on the self-healing process at three-dimension.Herein,we prepare monolayer self-he...Self-healing materials have been developed over the past decade with the recovery ability after damage.However,most researches focused on the self-healing process at three-dimension.Herein,we prepare monolayer self-healing hydrogen-bond-based supramolecular polymer film and explore the self-healing process at the two-dimensional limit.The healing process,which can be reversibly repeated for at least three times,is influenced by the temperature,the molecule-substrate interaction and the substrate roughness.In the application,the monolayer self-healing polymer film can be used to modify the SiO2 dielectric for copper phthalocyanine field effect transistor with improved mobility.This work will be valuable for developing two-dimensional functional self-healing materials in the future.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant No.61575096)
文摘Utilizing the periodically structured metal-organic framework （MOF） as the reaction vessel is a promising technique to achieve the aligned polymer molecular chains, where the diffusion procedure of the polymer monomer inside MOF is one of the key mechanisms. To investigate the diffusion mechanism of fluorinated polymer monomers in MOFs, in this paper the molecular dynamics simulations combined with the density functional theory and the Monte Carlo method are used and the all-atom models of TFMA （trifluoroethyl methacrylate） monomer and two types of MOFs,[Zn2（BDC）2（TED）]n and[Zn2（BPDC）2（TED）]n, are established. The diffusion behaviors of TFMA monomer in these two MOFs are simulated and the main influencing factors are analyzed. The obtained results are as follows. First, the electrostatic interactions between TFMA monomers and MOFs cause the monomers to concentrate in the MOF channel, which slows down the monomer diffusion. Second, the anisotropic shape of the one-dimensional MOF channel leads to different diffusion speeds of monomers in different directions. Third, MOF with a larger pore diameter due to a longer organic ligand,[Zn2（BPDC）2（TED）]n in this paper, facilitates the diffusion of monomers in the MOF channel. Finally, as the number of monomers increases, the self-diffusion coefficient is reduced by the steric effect.
文摘Self-organization in thin micro-films has shown potential for the production of microelements with specific structures and functions; however, little is known about its mechanism of formation. A 2-D molecular dynamics (MD) simulation on this process is carried out in this paper for films between two parallel walls (substrates) under different initial conditions. The films consist of two immiscible components (A and B). The simulation results in alternative columns perpendicular to the walls, which are rich either in A or in B molecules, respectively, apparently owing to their different interactions with the walls. The characteristic breadths of the columns depend on the distance between the two walls. By providing microscopic details of the self-organization processes and the resulted structures, MD simulation proves itself as a unique way for analyzing the dynamics of thin films.
基金supported by National Program for Thousand Young Talents of China,the National Natural Science Foundation of China(Nos.51773041,21544001,21603038)Shanghai Committee of Science and Technology in China(No.18ZR1404900)Fudan University
文摘Self-healing materials have been developed over the past decade with the recovery ability after damage.However,most researches focused on the self-healing process at three-dimension.Herein,we prepare monolayer self-healing hydrogen-bond-based supramolecular polymer film and explore the self-healing process at the two-dimensional limit.The healing process,which can be reversibly repeated for at least three times,is influenced by the temperature,the molecule-substrate interaction and the substrate roughness.In the application,the monolayer self-healing polymer film can be used to modify the SiO2 dielectric for copper phthalocyanine field effect transistor with improved mobility.This work will be valuable for developing two-dimensional functional self-healing materials in the future.
