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Electrophoretic flow of interacting polymer chains: Effects of temperature, polymer concentration, and porosity
Author(s) -
Foo Grace M.,
Pandey Ras B.
Publication year - 1998
Publication title -
macromolecular theory and simulations
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.37
H-Index - 56
eISSN - 1521-3919
pISSN - 1022-1344
DOI - 10.1002/(sici)1521-3919(19980301)7:2<283::aid-mats283>3.0.co;2-b
Subject(s) - polymer , chemistry , porosity , homogeneous , porous medium , analytical chemistry (journal) , thermodynamics , chromatography , physics , organic chemistry
Using a Monte Carlo simulation in three dimensions, we studied the variation of the root‐meansquare (rms) displacement ( R rms ) of polymer chains with time and the rates of their mass transfer ( j ) as a function of biased field ( B ), polymer concentration ( p ), chain length ( L c ), porosity ( p s ), and temperature ( T ). In homogeneous/annealed system, the rms displacement of the chains shows a drift‐like behavior, R rms ∼ t , in the asymptotic time regime preceded by a subdiffusive power‐law ( R rms ∼ t k , with k < 1/2) at high p . The subdiffusive regime expands on increasing L c and p but reduces on increasing T or B . In quenched porous media, the drift‐like behavior of R rms persists at low barrier concentration ( p b ) and high T . However, at high p b and/or low T , chains relax into a subdrift and/or subdiffusive behavior especially with high p or long L c . Flow of chains is measured via an effective permeability (σ) using a linear response assumption. In annealed system, σ increases monotonically with B at high T and low p but varies nonmonotonically at low T , high p and high L c . We find that σ decays with L c , σ ∼ L c −alpha; , where α depends on B, p and T with a typical value a α ∼ 0.43−0.64 for p = 0.1‐0.3 at B = 0.5. Further, σ decays with p , σ ∼ − Cp with a decay rate C sensitive to T and B . In quenched porous media, even at low pb and high T , σ varies nonmonotonically with bias, i.e., the increase of σ is followed by decay on increasing the bias beyond a characteristic value ( B c ). This characteristic bias seems to decrease logarithmically with barrier concentration, B c ∼ − k ln p b . The prefactor k depends on the chain length, k ≈ 0.35 for shorter chains ( L c = 20, 40) and ≈ 0.15 for longer chains ( L c = 60). Scaling dependence of σ on L c similar to that in annealed system is also observed in porous media with different values of exponent α. The current density shows a nonlinear power‐law response, j ∼ B σ , with a nonuniversal exponent δ ≈ 1.10−1.39 at high temperatures and low barrier concentrations.