Transport of star-branched polymers in nanoscale pipe channels simulated with dissipative particle dynamics simulation


Transport ofstar polymers under pressure-driven flow in apipe with pipe radius being at least twice the size of polymers has been examined with standard dissipative particle dynamics (DPD) simulations. Equilibrium dynamics of star polymers in bulk solution were found to obey the Zimm model very well, indicating that DPD simulation correctly incorporates the hydrodynamic interaction in the stars. Under pressure-driven flow, star polymers with more arms were found to migrate toward the center of pipe more, leading to a net faster velocity and hence a shorter retention time in the pipe. The stretching of star polymers along the flow was found to follow similar scaling behavior as the linear polymer chains, except that the Weissenberg number Wi for the stars should be reduced by arm number f. After rescaling of the Weissenberg number, the stretch ratio Sx, defined as the ratio of square of radius gyration of the chains along the flow, Rgx2, over its corresponding value in dilute bulk solution, was found to scale with Wi linearly when Wi. 1. The compression of the chains in the dimension perpendicular to the flow Sy were found to scale with Wi-0.5 when Wi » 1.0. © 2010 American Chemical Society.

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