Rod-like colloids and polymers in shear flow: a multi-particle-collision dynamics study

• Published in: Journal of physics. Condensed matter Vol. 16; no. 38; pp. S3941 - S3954
• Main Authors: Winkler, R G, Mussawisade, K, Ripoll, M, Gompper, G
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Bristol IOP Publishing 29.09.2004; Institute of Physics
• Subjects: Exact sciences and technology; Physics; Shear; Mean free path; Colloids; Chain length; Molecular dynamics method; Hydrodynamics; Relaxation time; Symmetry breaking; Mesoscale; Polymer solutions; Diffusion coefficient; Polymers; Self-diffusion
• ISSN: 0953-8984; 1361-648X
• DOI: 10.1088/0953-8984/16/38/012

The effect of the hydrodynamic interaction on the dynamics of flexible and rod-like polymers in solution is investigated. The solvent is simulated by the multi-particle-collision dynamics (MPCD) algorithm, a mesoscale simulation technique. The dynamics of the solvent is studied and the self-diffusion coefficient is calculated as a function of the mean free path of a particle. At small mean free paths, the hydrodynamic interaction strongly influences the dynamics of the fluid particles. This solvent model is then coupled to a molecular dynamics simulation algorithm. We obtain excellent agreement between our simulation results for a flexible polymer and the predictions of Zimm theory. The study of the translational diffusion coefficient of rod-like polymers confirms the predicted chain-length dependence. In addition, we study the influence of shear on the structural properties of rod-like polymers. For shear rates exceeding the rotational relaxation time, the rod-like molecule aligns with the shear flow, leading to an orientational symmetry breaking transverse to the flow direction. The comparison of the obtained shear rate dependencies with theoretical predictions exhibits significant deviations. The properties of the orientational tensor and the rotational velocity are discussed in detail as a function of shear rate.