Dimensional and Hydrodynamic Factors for Flexible Star Polymers in the Good Solvent Limit

Abstract

Star chains composed of arms with uniform length were generated on a simple cubic lattice by the Monte Carlo method using the enrichment algorithm, which enabled us to obtain chains with total segment numbers ( N ) up to 1200. The number of arms ( f ) ranged from 2 to 24. The radius of gyration (〈 S 2 〉 1/2 ), the dimensionless intrinsic viscosity ( E ), and the hydrodynamic radius ( R H ) were evaluated as functions of f and N by averaging over more than 4000 samples. The calculations of E and R H were made according to Zimm's method. It was found that the radius expansion factor (α S ) for star chains with long arms obeys the relation α S 2 = 1.53 z 2/5, which is known for long flexible linear chains, where z is the excluded volume parameter. The ratios of 〈 S 2 〉, E, and R H of star chains to those for linear chains were evaluated as functions of f . These ratios obtained and the Flory factors for the intrinsic viscosity and R H extrapolated to N -1/2 → 0 reproduced experimental data well.