The Size Of Ring Polymer In Explicit Solvents By Molecular Dynamics Simulations

Ring polymer has a unique structure and special physicochemical properties,and the experimental study of ring polymers is increasingly extensive.In order to investigate the relationship between the molecular dimension and structure,the changing trend of the mean square radius of gyration of ring polymer with different topologies in explicit solvent simulation is calculated by molecular dynamics simulations.First,molecular dynamics simulations are used to calculate the particle interaction parameters when the polymer is in the ? temperature in NVT and NPT ensemble respectively,after that the polymer solution phase diagram is plotted.Then,using the parameters of the phase diagram,which means square radius of the gyration of ring polymers with different topologies in good solvent and ? solvent is calculated respectively in the NVT ensemble.It expects that the present result is helpful for the study of ring polymers.There are four chapters in the dissertation as follows:Chapter 1: Introduction.This chapter mainly introduces the research background,research content and significance of the paper.First,the meaning and measurement method of ? temperature in solution are outlined.Furthermore,the research significance and the classification of ring polymers are summarized.Then,a brief history of the development about the molecular dynamics simulation and its research status are also reviewed.In the end,the main research about this paper is summarized.Chapter 2: ? temperature of the polymer solution and solution phase diagram.First of all,several methods to calculate the ? temperature of the polymer solution are summarized in the literature,and a new method to calculate the ? temperature based on form factor is proposed,then summarize the calculation principle and significance.Furthermore,using these different methods,the ? temperature of the solution in the implicit solvent is simulated to verify the accuracy of the new method in this paper.The ? temperature of polymer solution in NVT and NPT ensemble are calculated respectively and the phase diagram is plotted to prepare for the calculation of polymer dimension.Chapter 3: Calculation of the mean square radius of gyration of ring polymer.In this chapter,we research the relationship between the mean square radius of gyration and polymerization degree of rings for ring polymers with different topologies in a ? solvent and a good solvent.Firstly,we calculate the trend of the mean square radius of gyration of one tail,two tail and three tail ring polymers,then compare the simulation results with theoretical values.Finally,the mean square radius of gyration of ring polymer with complex structure is calculated,and the trend of the mean square radius of gyration of a ring polymer with different topologies is investigated.Chapter 4: Summary and prospect.This chapter summarizes the work done at this article,and briefly describes the follow-up work and development prospects in related fields.