The influence of the range of excluded volume interactions on the linear viscoelastic properties of dilute polymer solutions

The Rouse model has recently been modified to take into account the exclude d volume interactions that exist between various parts of a polymer chain b y incorporating a narrow Gaussian repulsive potential between pairs of bead s on the Rouse chain (Prakash, Macro molecules. 2001. 34, 3396-3411). The n arrow Gaussian potential is characterized by two parameters: z*-which accou nts for the strength of the interaction, and d*-which accounts for the rang e of the interaction. In the limit of d* going to zero., the narrow Gaussia n potential tends to the more commonly used delta -function repulsive poten tial. The influence of the parameter d*. in the limit of infinite chain len gth, on equilibrium and linear viscoelastic properties, and on universal ra tios involving these properties, is examined here. A renormalization group calculation of the end-to-end vector Suggests that the Value chosen for the variable d* will not affect critical exponents, or universal ratios. A sim ilar trend is also observed for results obtained with all approximate solut ion, which is based on the assumption that the non-equilibrium configuratio nal distribution function is Gaussian. (C) 2001 Elsevier Science Ltd. All r ights reserved.