Semiflexible Polymers Interacting With Planar Surfaces: Weak versus Strong Adsorption

Area of Science:

• Polymer Physics
• Soft Matter Physics
• Computational Materials Science

Background:

• Semiflexible polymers exhibit unique conformational properties influenced by chain stiffness and surface interactions.
• Understanding polymer behavior at interfaces is crucial for applications in coatings, biomaterials, and nanotechnology.
• Previous studies often simplified polymer-surface interactions or focused on flexible chains.

Purpose of the Study:

• To investigate the two-dimensionality of semiflexible polymers adsorbed to planar substrates.
• To quantify the influence of chain length, stiffness, and adsorption strength on polymer conformation.
• To elucidate the role of excluded-volume interactions in adsorbed polymer systems.

Main Methods:

• Utilized coarse-grained Molecular Dynamics simulations with a bead-spring polymer model.
• Varied chain length (N), stiffness (κ), and adsorption potential strength (ϵwall).
• Included and excluded excluded-volume (EV) interactions to model wormlike chains.

Main Results:

• Excluded-volume interactions negligibly affect local order parameters (f, η) for strongly adsorbed chains.
• Mean square gyration radius parallel to the wall (⟨Rg²⟩∥) is significantly influenced by EV when chain length exceeds persistence length.
• Perpendicular dimensions (⟨Rg²⟩⟂) and local order parameters converge with 1/N corrections; monomer positions perpendicular to the wall show correlations.

Conclusions:

• Semiflexible polymers adsorbed to surfaces deviate from strict two-dimensionality, particularly concerning their parallel dimensions.
• Excluded-volume effects are critical for accurately describing the conformational behavior of adsorbed semiflexible polymers.
• Simulation results provide insights for interpreting experimental data on adsorbed polymer systems.