Parameters influencing diffusion dynamics of an adsorbed polymer chain

Prior research has shown that polymer chain diffusion is influenced by factors like chain length and solvent conditions. However, the specific role of chain flexibility and hydrodynamic interactions remains unclear. Established knowledge suggests that adsorbed polymers exhibit unique mobility patterns. This paper addresses a gap in understanding how chain architecture affects diffusion dynamics. No prior work had resolved the interplay between chain flexibility and hydrodynamic interactions. Existing models often assume idealized conditions not found in real systems. This uncertainty motivated a more detailed simulation-based investigation. The study builds on foundational work in polymer physics and computational modeling.

The aim of this study is to determine how chain length affects the diffusion of adsorbed polymer chains. The specific problem involves understanding the relationship between chain architecture and translational diffusivity. The motivation comes from the need to predict polymer behavior on surfaces accurately. This work seeks to clarify the role of hydrodynamic interactions in diffusion dynamics. The study focuses on polymer chains adsorbed onto flat surfaces. The authors investigate how chain flexibility influences scaling exponents. They also explore the effect of solvent quality on diffusion behavior. The goal is to provide a more complete picture of adsorbed polymer mobility.

Brownian dynamics simulations are used to model polymer chain diffusion. Hydrodynamic interactions are incorporated using the no-slip boundary condition. Two types of chains are simulated: bead-rod and bead-spring configurations. Hookean and FENE springs are used to model chain flexibility. The simulations track translational diffusivity in the planar direction. Chain lengths up to 100 beads are considered in the study. The scaling exponent nu is calculated for each configuration. The effects of chain flexibility, hydrodynamic interactions, and solvent quality are analyzed.

The translational diffusivity D{ parallel} scales with N^{-nu}, where N is chain length. For bead-rod chains and stiff FENE springs, nu is approximately 0.75. With flexible FENE and Hookean springs, nu increases to 1. The scaling exponent depends on chain flexibility, hydrodynamic interactions, and solvent quality. Near homogeneous surfaces, nu changes from 0.75 to 1 with increased flexibility. A decrease in hydrodynamic interaction strength also increases nu to 1. Poorer solvent quality leads to the same change in nu. On heterogeneous surfaces, nu remains at 1 regardless of other factors.

The authors propose that chain flexibility is a key determinant of scaling behavior. They suggest that hydrodynamic interactions influence diffusion dynamics significantly. The study confirms that solvent quality affects the scaling exponent nu. The findings indicate that heterogeneous surfaces stabilize the scaling exponent at 1. The results align with theoretical predictions for polymer adsorption behavior. The authors emphasize the importance of chain architecture in diffusion studies. They note that flexible chains exhibit a different scaling regime than rigid ones. The study provides a framework for understanding polymer mobility on surfaces.