We investigate configuration dynamics of a flexible polymer chain in a bath of active particles with dynamic chirality, i.e., particles rotate with a deterministic angular velocity ω besides selfpropulsion,by Langevin dynamics simulations in two dimensional space. Particular attentions are paid to how the gyration radius Rg changes with the propulsion velocity v0,angular velocity ω and chain length. We find that in a chiral bath with a typical nonzero ω, the chain first collapses into a small compact cluster and swells again with increasing v0, in quite contrast to the case for a normal achiral bath (ω = 0) wherein a flexible chain swells with increasing v0. More interestingly, the polymer can even form a closed ring if the chain length is large enough,which may oscillate with the cluster if v0 is large. Consequently, the gyration radius Rg shows nontrivial non-monotonic dependences on v0, i.e., it undergoes a minimum for relatively short chains, and two minima with a maximum in between for longer chains. Our analysis shows that such interesting phenomena are mainly due to the competition between two roles played by the chiral active bath: while the persistence motion due to particle activity tends to stretch the chain, the circular motion of the particle may lead to an effective osmotic pressure that tends to collapse the chain. In addition, the size of the circular motion R0 = v0/ω shows an important role in that the compact clusters and closed-rings are both observed at nearly the same values of R0 for different ω.arXiv:1908.09099v1 [cond-mat.soft]

Configuration dynamics of flexible polymer chains is of ubiquitous importance in many biological processes. Here, we investigate a polymer chain immersed in a bath of size-changed active particles in two dimensional space using Langevin dynamics simulations. Particular attention is paid to how the radius of gyration Rg of the polymer chain depends on the size σc of active crowders. We find that Rg shows nontrivial non-monotonic dependence on σc: The chain first swells upon increasing σc, reaching a fully expanded state with maximum Rg, and then, Rg decreases until the chain collapses to a compact coil state if the crowder is large enough. Interestingly, the chain may oscillate between a collapse state and a stretched state at moderate crowder size. Analysis shows that it is the competition between two effects of active particles, one stretching the chain from inside due to persistence motion and the other compressing the chain from outside, that leads to the non-monotonic dependence. Besides, the diffusion of the polymer chain also shows nontrivial non-monotonic dependence on σc. Our results demonstrate the important interplay between particle activity and size associated with polymer configurations in active crowding environments.