(313g) DNA as Model Polymer for Viscoelastic Flow Analysis

The microstructure and the behavior of individual polymer chain affect the macroscopic flow of polymer solution and melt, especially in complicated geometry. The conventional experiment techniques such as light scattering or flow birefringence cannot observe single molecular dynamics. Consequently, the measured properties from these methods only show an averaged effect. Similarly, closed-form constitutive equations used in current numerical simulation cannot predict many flow behaviors in viscoelastic fluids. In this study, we use fluorescence dye labeled DNA molecules as a model polymer and spin-disk confocal microscopy to investigate the contraction-expansion flow and the fountain flow widely observed in polymer processing using micro-fabricated flow devices. Mesoscopic CONNFFESSIT method and coarse-grained Brownian dynamics simulation method are used to simulate single molecular dynamics in viscoelastic flow. The stretching and relaxation of DNA chains in these complicated flows are analyzed both experimentally and numerically.