Flow of polymer chains and segregation in a flow field with a hybrid simulation

Effects of a flow field (E) on segregation and flow of polymer chains are s tudied in two dimensions using a hybrid (discrete-to-continuum) simulation. The flow rate (j) of polymer chains is found to increase monotonically wit h E, a linear response in the low field regime followed by a slow approach to saturation in the high field regime. The effective chain permeability (p hi(c) = j/E) varies nonmonotonically on increasing the field E, with a maxi mum (phi(cm)) at a characteristic value of the field tin the range 0.2 < E < 2); phi(cm) depends on the chain length. Chain aggregates exhibit an anis otropic mass distribution due to the field with a molecular bridging at hig h fields. The longitudinal component of the radius of gyration (R-gx) exhib its a crossover from a random walk (RW) (R-gx similar to L-c(1/2)) at E = 0 to an elongated conformation (R-gx similar to L-c) at E greater than or eq ual to 0.2; the transverse component changes from R-gy similar to L-c(1/2) to R-gy similar to L-c(1/3). The width of the radial distribution function (p(r)) of the monomers increases while its peak varies nonmonotonically wit h E and is consistent with the observation of anisotropic mass distribution .