Study On Self-assembly Kinetics Of Oil-water Interface Nanoparticles

With the development of nanotechnology,the research of interfacial self-assembly and amphiphilic nanoparticles is gradually deepened.Self-assembled nanoparticles interface has potential scientific value,different metal nanoparticles interface self-assembly configurations have different optical properties,photovoltaic electric field,in addition,the self-assembly of inorganic nanoparticles interface in the chemical catalyst,Pickering emulsion production,drug delivery and material preparation,etc also has very important significance.However,at the nanoscale,nanoparticles show significant non-equilibrium dynamics in the complex microscopic force field,and it is very difficult to accurately describe their motion characteristics,which has become a hot research field.Therefore,revealing the dynamic behavior and mechanism of interfacial self-assembly of nanoparticles is the key to predict and regulate the interfacial self-assembly configuration of nanoparticles.The nanoscale effects of nanoparticles on the interface include pinning effect and molecular thermal fluctuation effect.The self-assembly behavior of nanoparticles interface is also influenced by transverse capillary effect induced by surface defects and separation pressure of symmetry break.In this thesis,molecular dynamics method was adopted to establish the all-atom model.Under the GROMOS field,interatomic forces are divided into van der Waals force and Coulomb force,and are constrained by bonds,bond angles and dihedral angles.The specific research contents are as follows:The model of amphiphilic nanoparticles and oil-water interface was established,and the accuracy of the model was verified by comparing with the surface tension measured in experiments.Molecular dynamics simulation was used to study the dynamic behaviors of amphiphilic nanoparticles with different sizes,shapes and hydrophobic modification ratios at the interface,such as translational,rotational,contact Angle,diffusion coefficient,radial distribution of oil and water molecules,etc.It was found that silica with 25%methyl modification ratio was more stable at the interface.For the spontaneous adsorption of multiple particles on the interface,it is found that the interface saturation remains unchanged at 0.20 particles/nm~2 with the increase of the interaction force between particles,while nanoparticles precipitate when the saturation reaches 0.47 particles/nm~2 when forced particles are added on the interface.In the ordered structure of larger nanoparticles,the interface configuration changes when the saturation reaches a certain condition,forming a concave and convex interface.With the increase of saturation,the interface is more stable.By molecular dynamics method,constructs the oil-water interface all atomic model,in view of the self-assembly of nanoparticles in the oil-water interface behavior and the regulation mechanism is not clear problem,carry out research on the effects of nanoparticles and the oil-water interface interaction,studied the different shapes,sizes,and feeling of water-based group of amphiphilic the dynamics behavior of nanoparticles in the oil-water interface,And the dynamic behavior and interface behavior of multi-nanoparticle at oil-water interface.