Dynamics of a two-dimensional active polymer chain with a rotation-restricted active head.

Hu, Han-Xian; Shen, Yi-Fan; Wang, Chao; Luo, Meng-Bo · Soft Matter · 2022

basic_science · Level V

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Abstract

The dynamics of a two-dimensional active polymer composed of an active Brownian particle (ABP) at the head and a passive polymer chain is investigated using Langevin dynamics simulation. The ABP experiences a self-propulsion force <b><i>f</i></b><sub>s</sub> and a resistance torque <b><i>M</i></b> as the passive polymer chain is bonded to the edge of the ABP. <b><i>M</i></b> restricts the rotation of the ABP, and thus the dynamics of the ABP and that of the whole active polymer are influenced significantly. Due to this restriction, the persistence time <i>τ</i><sub>r</sub>, which characterizes the random rotation of the ABP, is increased significantly and changes non-monotonically with the rotational friction coefficient <i>η</i><sub>r</sub>. Our simulation results show that the effect of <b><i>M</i></b> on the dynamics of the active polymer can be characterized mainly by the change of <i>τ</i><sub>r</sub>. Moreover, the propulsive diffusion coefficient <i>D</i><sub>P</sub> of the whole polymer chain originated from the self-propulsion force can be described by a scaling relation <i>D</i><sub>P</sub> ∝ <i>f</i><sub>s</sub><sup>2</sup><i>τ</i><sub>r</sub>/<i>N</i><sup>2</sup><i>η</i><sub>t</sub><sup>2</sup> with <i>η</i><sub>t</sub> the translational friction coefficient and <i>N</i> the polymer length. Our results show that the diffusion is promoted by the resistance torque <b><i>M</i></b> and <i>τ</i><sub>r</sub> is a key factor for the diffusion of active polymers.