Dynamics of linear polymers in dilute solutions

We present an exactly soluble Rouse-like model of the linear polymer chain dynamics in which the effects of solvent molecule dynamics and ultrasonic absorption are treated. Calculations for the relaxation time spectra, total intrinsic viscosity [eta(T)(omega)], intrinsic viscosity [eta(omega)], elastic modulus G(omega) and specific heat capacity C(omega) of the polymer are presented in the free-draining limit. The calculations were carried out according to the configuration interaction method currently used in quantum mechanics. The relaxation time spectrum corresponding to dynamics of low frequency modes shows a Rouse-like character, whereas the relaxation time spectrum associated with dynamics of moderate frequency modes is narrower. The behaviour of the intrinsic viscosity [eta(omega)] and elastic modulus G(omega) are shown to be represented by the model within the low frequency range. In the moderate- and high-frequency regions, [eta(omega)] drops to zero and [eta(T)(omega)] reaches a plateau value equal to the sum of both the single bead intrinsic viscosity [eta(N)] and the effective solvent intrinsic viscosity [eta(eff)]. Behaviour of the specific heat capacity C(omega) is shown to be represented by the model at acoustic frequency region. The model is shown to be Rouse-like and representative for the description of ultrasonic absorption studies. (C) 1999 Elsevier Science B.V. All rights reserved.