Linear Viscoelasticity of Semidilute Unentangled Flexible Polymer Solutions

Abstract

The linear viscoelastic response of flexible polymer solutions in the dilute and semidilute unentangled regimes is investigated using Brownian dynamics simulations. The relaxation modulus and dynamic moduli are computed over a wide range of concentrations and chain discretizations for both $\theta$ and good solvents. In the dilute limit, simulations recover Zimm-like behavior with solvent-quality-dependent power-law scaling in the intermediate time and frequency regimes, while in the semidilute unentangled regime a systematic crossover to Rouse-like dynamics is observed with increasing concentration due to screening of excluded-volume and hydrodynamic interactions. Comparison with experimental measurements shows excellent agreement for the storage modulus across both concentration regimes and for the loss modulus at low and intermediate frequencies, with deviations at high frequencies due to finite-chain discretization effects. Systematic accounting for these finite-chain length effects using successive fine-graining enables quantitative prediction of the loss modulus in the infinite-chain length limit.

19 pages, 13 figures, to appear in Industrial & Engineering Chemistry Research

References in corpus (13)

• Semidilute Polymer Solutions at Equilibrium and under Shear Flow
• Rapid Sampling of Stochastic Displacements in Brownian Dynamics Simulations
• Screening of Hydrodynamic Interactions in Semidilute Polymer Solutions: A Computer Simulation Study
• Universal dynamics of dilute and semidilute solutions of flexible linear polymers
• Universal solvent quality crossover of the zero shear rate viscosity of semidilute DNA solutions
• Viscometric Functions for a Dilute Solution of Polymers in a Good Solvent
• Parameter-free prediction of DNA dynamics in planar extensional flow of semidilute solutions
• Fluctuation-dissipation relation between shear stress relaxation modulus and shear stress autocorrelation function revisited
• The origin of dynamic scaling in dilute polymer solutions
• Dynamic crossover scaling in polymer solutions
• The viscosity radius in dilute polymer solutions: Universal behaviour from DNA rheology and Brownian dynamics simulations
• Universality of the collapse transition of sticky polymers
• Evanescent Gels: Competition Between Sticker Dynamics and Single Chain Relaxation