Molecular Dynamics Simulation Of Fluids In Polyvinylidene Fluoride Nanochannels

Poly(vinylidene fluoride)(PVDF)is a new polymer membrane material with excellent performance,which exhibits good chemical resistance,thermal stability and mechanical stability.Hydrophilic modification of PVDF to improve the anti-pollution ability of materials is a hot issue in the field of membrane science.However,theoretically explaining the relationship between the microstructure of the membrane surface and the hydrophilicity and anti-fouling ability of the membrane remains to be studied.With the development of science technology and the expansion of computer application field,it is a trend to apply traditional experiment to computer simulation,which can reduce unnecessary waste of resources,negate some irrational experimental conjectures and achieve the expected purpose by simulating.In this paper,molecular dynamics simulation method was used to establish the PVDF membrane model and the motion of the fluid in the nanometer PVDF membrane channel was studied for the performance of PVDF membrane.It is helpful to study the surface effect of fluid flow that the nano-channel model is used to simulate the movement of fluid in the PVDF membrane channel.The motion law of the surface affiliation asymmetric channel,the motion characteristics of the fluid and the influence of the membrane surface properties on the fluid were studied in the nano-channel.The PVDF crystal model is established by using the Dmol^3 module of Material Studio 6.0 and the geometric structure is optimized.Subsequently,combining with the literature to establish the force field parameters,the PVDF film was sintered by raising the temperature and the membrane system was obtained by cooling step by step.Molecular dynamics simulations were performed by LAMMPS software.The results show that The molecular distribution of the fluid in the molten PVDF membrane is more uniform and the hydrophilicity is improved.The effect of methanol solution and aqueous solution on the membrane surface properties is not obvious.The PVDF nano-channels with different pore diameters have some influence on the distribution of solution molecules in the channels,which was the larger the pore size,the more uniform the distribution of the solution.