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

Abstract

Effects of a flow field (E) on segregation and flow of polymer chains are studied in two dimensions using a hybrid (discrete-to-continuum) simulation. The flow rate (j) of polymer chains is found to increase monotonically with 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 (Φ c = j/E) varies nonmonotonically on increasing the field E, with a maximum (Φ cm ) at a characteristic value of the field (in the range 0.2 <E < 2); Φ cm depends on the chain length. Chain aggregates exhibit an anisotropic mass distribution due to the field with a molecular bridging at high fields. The longitudinal component of the radius of gyration (R gx ) exhibits a crossover from a random walk (RW) (R gx ∼ L c 1/2 ) at E = 0 to an elongated conformation (R gx ∼ L c ) at E ≥ 0.2; the transverse component changes from R gy ∼ L c 1/2 to R gy ∼ L c 1/3 . The width of the radial distribution function (p(r)) of the monomers increases while its peak varies nonmonotonically with E and is consistent with the observation of anisotropic mass distribution.