Detachment of semiflexible polymer chains from a substrate: A molecular dynamics investigation

J Paturej and A Erbas and A Milchev and VG Rostiashvili, JOURNAL OF CHEMICAL PHYSICS, 141, 214902 (2014).

DOI: 10.1063/1.4902551

Using Molecular Dynamics simulations, we study the force-induced detachment of a coarse-grained model polymer chain from an adhesive substrate. One of the chain ends is thereby pulled at constant speed off the attractive substrate and the resulting saw-tooth profile of the measured mean force < f > vs height D of the end-segment over the plane is analyzed for a broad variety of parameters. It is shown that the observed characteristic oscillations in the < f >-D profile depend on the bending and not on the torsional stiffness of the detached chains. Allowing for the presence of hydrodynamic interactions (HI) in a setup with explicit solvent and dissipative particle dynamics-thermostat, rather than the case of Langevin thermostat, one finds that HI have little effect on the < f >-D profile. Also the change of substrate affinity with respect to the solvent from solvophilic to solvophobic is found to play negligible role in the desorption process. In contrast, a changing ratio epsilon(B)(s)/epsilon(A)(s) of the binding energies of A-and B-segments in the detachment of an AB-copolymer from adhesive surface strongly changes the < f >-D profile whereby the B-spikes vanish when epsilon(B)(s)/epsilon(A)(s) < 0.15. Eventually, performing an atomistic simulation of (bio)-polymers, we demonstrate that the simulation results, derived from our coarse-grained model, comply favorably with those from the all-atom simulation. (C) 2014 AIP Publishing LLC.

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