Dissipative particle dynamics simulation of on-chip hydrodynamic chromatography

Separations of flexible polymers using on-chip hydrodynamic chromatography (HDC) have been studied with dissipative particle dynamic simulations, a novel computational technique that fully accounts for hydrodynamic interactions among polymer segments and with walls. The current study focuses on comparisons of simulation results on elution times with that predicted by earlier theoretical models for HDC separation. The elution times obtained in simulation are found to compare reasonably well with the theoretical prediction when chain stretching is not significant. Deviation from the theoretical prediction occurs when the chain stretching becomes significant. We observe a reversal in elution order and the reversal occurs at a Deborah number about 8, slightly larger than the Deborah number at the onset of chain stretching. The simulations also confirm the applicability of the Aris-Taylor equation for the convective dispersion of small solutes and for solutes like polymer chains, except the latter requires the use of a modified Peclet number.