Linear Dimensions of Adsorbed Semiflexible Polymers: What can be learned about their persistence length?

TL;DR

This study investigates how the conformations of adsorbed semiflexible polymers depend on stiffness and adsorption strength, revealing deviations from classical models and implications for experimental interpretation.

Contribution

It provides a detailed analysis of polymer conformations and persistence length crossover, challenging the applicability of the wormlike chain model for adsorbed chains.

Findings

Partially adsorbed chains are not described by the wormlike chain model.

Persistence length crossover from 3D to 2D is characterized.

Adsorption threshold scales as the inverse cube root of persistence length.

Abstract

Conformations of partially or fully adsorbed semiflexible polymer chains are studied varying both contour length $L$, chain stiffness, $\kappa$, and the strength of the adsorption potential over a wide range. Molecular Dynamics simulations show that partially adsorbed chains (with "tails", surface attached "trains" and "loops") are not described by the Kratky-Porod wormlike chain model. The crossover of the persistence length from its three-dimensional value $(\ell_p)$ to the enhanced value in two dimensions $(2\ell_p)$ is analyzed, and excluded volume effects are identified for $L \gg \ell_p$. Consequences for the interpretation of experiments are suggested. We verify the prediction that the adsorption threshold scales as $\ell_p^{-1/3}$.