title: The theta-temperature depression caused by topological effect in ring polymers studied by Monte Carlo simulation.
abstract: We studied equilibrium conformations of linear and ring polymers in dilute solutions over the wide range of segment number N of up to 2048 with Monte Carlo simulation, and evaluated N dependence of the radii of gyration, R(g), of chains. The polymer molecules treated in this study are assumed to be composed of beads and bonds, and they are put in a three-dimensional face-centered cubic (FCC) lattice. The values of Flory's critical exponent, ν, for linear and ring polymers were estimated from the N dependence of R(g), and the temperatures at which ν reach 1/2 were obtained. Here we define those as Θ-temperatures in this report. The simulation result shows that the Θ-temperature for ring polymers is evidently lower than that of the linear polymers, and the origin of the Θ-temperature depression is discussed. Since R(g) of a ring polymer is smaller than that for a linear polymer at the same N and temperature, the segment density for a ring polymer is increased by the topological effect and the repulsive force between segments of a ring polymer at the Θ-temperature for a linear polymer is stronger. Thus, the origin of the Θ-temperature depression for ring polymers is the repulsive force emphasized by the topological effect of rings.
authors: Computing Research Center, High Energy Accelerator Research Organization, KEK, Oho 1, Tsukuba, Ibaraki 305-0801, Japan. jiro.suzuki@kek.jp
authors: Jiro
authors: J
authors: Suzuki
authors: Atsushi
authors: A
authors: Takano
authors: Yushu
authors: Y
authors: Matsushita