不同拓扑结构环形聚合物刷的静态结构和动力学性质的研究理论物理专业论文.docxVIP

万方数据 万方数据 II AbstractPolymer Abstract Polymer brushes are depicted as layers of long-chain polymer molecules tethered by one end to a substrate surface．The study of polymer brush is important in many applications，such as polymer adhesion，colloidal stabilization，lubrication，and DNA segregation in bacteria．In recent years，there has been a great interest in the properties of ring polymer for mathematical，simulation，and experimental scientists．The configuration of ring polymer in melt solution plays a significant role in most biological systems，making it a hot research topic in polymer physics．Flory theory suggests that behaviors of linear polymer chains are similar to those of trivial Gaussian chains，for gyration radius，both complying with a Flory exponent V=1／2 scaled as R6～Nv in melts due to volume-excluded effect．However,even such simple scaling law is not suitable for ring polymers By defining a topological constraint value(rn)static and dynamic properties of polymer brush composed of moderate or short chains witll different topological ring structures are studied using molecular dynamics simulation，and a comparison with those of linear polymer brush is also made．For the center-of-mass height of ring polymer brush scaled by chain length h—NV，there is no significant difference of exponent from that of linear brush in the small topological constraint regime．However， as the topological constraint becomes stronger,one obtains smaller exponent．It is found that there exists a master scaling power law of the total stretching energy scaled by chain length N for moderate chain length regime，最ne～ⅣJDV，for ring polymer brushes， but with a larger exponent V than 5／6，indicating an influence of topological constraint to the dynamic properties ofthe system．We have simulated an isothermal compression ofthe brushes，a topological invariant of free energy scaled by《c)叭／is found． Key words：ring polymer；scaling；isothermal compression；topological invariant； III IV 目录摘要 目录 摘要 ．． I Abstrac