Adsorption Kinetic Behaviors of a (Semi)flexible Self-Propelling Filament between Two Homogeneous Attractive Surfaces

Abstract

The structural and kinetic behaviors of the (semi)flexible self-propelling filament (SPF) during adsorption between two homogeneous attractive surfaces were investigated by Langevin dynamics simulation, mainly exploring the effects of the active force (Pe), chain rigidity (κ), and distance (Dz) between two attractive interfaces. We found that the flexible SPF exhibits two different adsorption mechanisms: the superdiffusion region adsorption at a smaller Pe and the normal-diffusion region adsorption at a larger Pe. During adsorption in the normal-diffusion regime, the adsorption time (τads) is inversely proportional to the diffusion coefficient (D∥) of the flexible SPF center of mass in the direction parallel to the interface and is also proportional to the square of Dz, i.e., τads ∼ D∥–1Dz2. Due to the intense competition between κ and Pe, the τads of the semiflexible SPF exhibits a nonmonotonic dependence on Pe, initially decreasing, then increasing, and finally decreasing again. When κ is relatively large, as Pe increases, the semiflexible SPF undergoes four sequential adsorption modes: adsorption in the superdiffusion, ballistic, transition, and normal-diffusion regimes. During adsorption in the ballistic regime, the semiflexible SPF is captured by the interface with a “rod-like” conformation, and τads is inversely proportional to Pe, i.e., τads ∼ Pe–1. When transitioning from the ballistic regime adsorption mode to the transition regime adsorption mode, an optimal Pe facilitates the more rapid completion of the adsorption of the semiflexible SPF. Our study advances our active polymer interfacial behavior understanding, establishes key theoretical frameworks for experiments, and provides mechanistic insights into their interfacial dynamics in complex crowded environments.