| With the rapid development of nanotechnology,nanomaterials have been widely used in biomedical fields such as biosensors,drug delivery,chemotherapy and so on.the dispersion ability of nanomaterials in water and the wetting behavior of nano-surface droplets have also been widely concerned.In this paper,through molecular dynamics simulation,fullerene model and graphene are used as the model system to simulate different polar unit densities by uniformly distributing different number of positively charged and negatively charged atomic sites on the model surface.to explore the effect of polar unit density on the water solubility and surface water wettability of nanoparticles.Using C60 as the model system,nanoparticles with different polar unit densities were obtained by distributing atomic charges on the surface of C60.The effects of polar unit density on the water solubility and hydration properties of nanoparticles were systematically studied by molecular dynamics simulation.After the introduction of surface polarity,the water solubility of nanoparticles increased rapidly,but when the number of polar atoms on the surface of C60 exceeded a certain level,the water solubility of nanoparticles changed little.The dependence of the water solubility of nanoparticles on the density of surface polar units may be related to the interaction of different aspects of the hydration behavior of nanoparticles.The strong interaction between hydrated water and nanoparticles,the weak interaction between contacted nanoparticles,and the formation of more hydrogen bonds between water molecules in the hydrated layer and other water molecules are beneficial to the dispersion of nanoparticles,and they all change non-monotonously with the change of polar unit density.In addition,the hydration structure of nanoparticles also changes with the density of polar units rather than monotonously.This discovery contributes to a better understanding of the water solubility and hydration behavior of polar nanomaterials and biomolecules on the nanometer scale.Using graphene as the model system,the effect of the coverage density of polar units on the nano-plate surface on the water wettability of the nano-plate was studied systematically.After the introduction of surface polarity unit,the wettability is enhanced.However,with the increase of the proportion of polar charge distribution in the nano-plate,the water wettability of the nano-plate changes non-monotonously.The introduction of surface polarity enhances the interaction potential between water molecules and nano-plates in the first water molecular layer,which is beneficial to the enhancement of wettability,but the dependence between the distribution ratio of surface polarity and the interaction potential is not monotonous.On the other hand,the surface polarity also interferes with and rearranges the water molecular structure of the first water molecular layer on the surface of the nano-plate,and it also changes non-monotonously with the change of surface polarity.The relationship between the wettability of nanoplates and the density of surface polar units is largely attributed to the interaction of different aspects of surface hydration behavior.This study is helpful to understand the mechanism of wettability and the preparation of charged nano-plate functional materials. |
