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Download file# Effect of Topology on the Statics and Dynamics of a Polymer Chain at the Fluid–Fluid Interface: A Molecular Dynamics Simulation Study

journal contribution

posted on 2022-05-13, 22:05 authored by Jenis Thongam, Lenin S. ShagolsemThe
effect of chain topology on the statics and dynamics of a chain
at the interface of two immiscible fluids is studied by means of molecular
dynamic simulations. For three topologically different chains, namely,
linear, ring, and trefoil-knot, of the same molecular weight, the
effect of varying both polymer–fluid and fluid–fluid
interaction nature on the width of the fluid interface, chain conformation,
shape, and chain dynamics is investigated. For a sharp-interface binary-fluid
system, the interface width is insensitive to both topology and polymer–fluid
interaction nature, while a weak nonmonotonic variation is seen for
a broad-interface system. Chain extension normal to the interface
plane is significantly affected by the topology with a trefoil-knot
chain, due to the additional constraint, which has the largest value
compared to both linear and ring polymers. Instantaneous shapes are
also quantified through shape parameters. Furthermore, it is observed
that the qualitative behavior of the center-of-mass mean-square displacement
(MSD) is independent of topology, i.e., all the chain types show the
same diffusion exponent α ( ∼ 1). However, the self-diffusion
constant depends on the topology and it is the largest for the trefoil-knot
chain. An interesting observation pertaining to the early time behavior
of monomeric MSD is that, within the subdiffusive regime, the values
of α for different parameters (independent of topology) are
grouped into two distinct ranges (0.52 – 0.59 and 0.62 –
0.67), which are related to the different chain conformation for the
polymer–fluid interaction range below and above a threshold
value equal to that of the self-interaction of the pure fluid phase.

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∼ 1 ).weak nonmonotonic variationtwo immiscible fluidstwo distinct rangesthreshold value equalinteresting observation pertainingdiffusion constant dependspure fluid phasemolecular dynamic simulationsearly time behavior62 – 052 – 0chain types showchain extension normalpolymer – fluidlargest value compareddiffusion exponent αdifferent chain conformationpolymer chainchain conformationqualitative behaviormolecular weightfluid systemdifferent parametersfluid interfacesubdiffusive regimesquare displacementsignificantly affectedmass meaninstantaneous shapese .,also quantifiedadditional constraint67 ),