ISSN:
1089-7690
Source:
AIP Digital Archive
Topics:
Physics
,
Chemistry and Pharmacology
Notes:
Aggregation and flow of polymer chains (each of length Lc) on a heterogeneous surface are studied in presence of a field E using a hybrid simulation. Effects of field, heterogeneity (i.e., the barrier concentration pb), and temperature T on aggregation and desegregation of chains with low molecular weight is found to be different from that with high molecular weight. For low Lc, at low T=0.2, the impurity barriers act as seeds for pinning the growth of molecular aggregates that lead to larger aggregates at lower pb. At high temperature (T=1.0), in contrast, larger aggregates appear at higher pb where pinning of aggregates is augmented by cluster of clustering. For large Lc, orientational ordering with a molecular bridging occurs at low pb, while a nearly isotropic network of chains anchored by the barriers emerges at higher pb. The rms displacement of chain ranges from drift-like for short chains at low barrier concentration to strongly subdiffusive for long chains at high fields. A linear response of the flow rate density j to field j∼E is observed over low to moderate fields (E≤1.0), high temperature (T≥1), and low barrier concentrations (pb≤0.1). The variation of the effective linear permeability φm of polymer with the field is nonmonotonic over the range 0.0〈E〈1.0, with decreasing trend at higher values of E. In the low field regime (E〈0.2), the monomer permeability shows a power-law decrease with chain length φm∼Lc−α, α(similar, equals)0.25–0.37. © 2000 American Institute of Physics.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.481699
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