Conformational Properties of Active Semiflexible Polymers

Abstract

Abstract:The conformational properties of flexible and semiflexible polymers exposed to active noise are studied theoretically. The noise may originate from the interaction of the polymer with surrounding active (Brownian) particles or from the inherent motion of the polymer itself, which may be composed of active Brownian particles. In the latter case, the respective monomers are independently propelled in directions changing diffusively. For the description of the polymer, we adopt the continuous Gaussian semiflexible polymer model. Specifically, the finite polymer extensibility is taken into account, which turns out to be essential for the polymer conformations. Our analytical calculations predict a strong dependence of the relaxation times on the activity. In particular, semiflexible polymers exhibit a crossover from a bending elasticity-dominated dynamics to the flexible polymer dynamics with increasing activity. This leads to a significant activity-induced polymer shrinkage over a large range of self-propulsion velocities. For large activities, the polymers swell and their extension becomes comparable to the contour length. The scaling properties of the mean square end-to-end distance with respect to the polymer length and monomer activity are discussed.

Conformational and dynamical properties of semiflexible polymers in the presence of active noise

“…Interestingly, semiflexible polymers exhibit an activityinduced shrinkage. However, for large activities the polymer conformations are ultimately comparable with those of flexible polymers [36]. Moreover, we find a substantially enhanced diffusion of the active polymers, with three distinct regimes: a ballistic regime for short times, a Rouse-type polymer specific regime for intermediate times, and free diffusion for long times [38].…”

“…Within the Gaussian semiflexible polymer model, the polymer is considered as a continuous, differentiable space curve r(s, t), with the contour coordinate s along the linear chain of length L (−L/2 < s < L/2) and the time t [36,38,48,50,51]. The equation of motion of r(s, t) is given by the Langevin equation [36,38,[52][53][54][55][56] …”

“…For a polymer, activity can be interpreted in two ways. On the one hand, our polymer can be considered as comprised of active monomers, e.g., active Brownian particles [21,22,35,36,38,40]. On the other hand, the active force may originate from interactions with uncorrelated surrounding ABPs, hence, the polymer corresponds to a passive polymer dissolved in an active bath [30,41,42].…”

“…We adopt the Gaussian semiflexible polymer model [48,49] composed of ABPs, which allows us to treat the problem analytically [36,38]. Thereby, we account for the finite polymer extensibility and demonstrate that it strongly affects polymer relaxation behavior and dynamics.…”

Dynamically generated patterns in dense suspensions of active filaments

“…While it is not surprising that the diffusion coefficient increases with activity (see also Ref. [53]), the origin of the linear dependence on the Pe is at present not clear. Stiffer filaments, on the other hand, exhibit a transition from subdiffusive to superdiffuisive flow at Pe ≈ 1.…”