Configuration Dynamics of Active Polymer Chain with Actively Driven Regions

Langevin dynamics simulations were implemented to investigate the configuration dynamics of a polymer chain in two-dimensional space. The polymer chain we studied consists of two types of beads: passive Brownian particles and active Brownian particles. Special attention was paid to the dependence of the radius of gyration R_g of the polymer chain on the ratio of active sites \phi . We found that as the ratio of active sites \phi increases, the radius of gyration R_g of a flexible chain increases monotonically, whereas for a semi-flexible polymer chain, the radius of gyration R_g exhibits a non-monotonic variation. Moreover, when the ratio of active sites \phi is fixed, the radius of gyration R_g of the polymer chain also exhibits a non-monotonic variation as the activity increases. Analysis reveals that it is the interplaybetween two effects of active semi-flexible chain, one is the stretching effect of the polymer chain due to rigidity, which straightens the polymer chain and makes the chain swell, the other is the active induced folding effect of the polymer chain, the active force makes the polymer chain collapse. Once the ratio of active sites is large enough, the activity acts as an effective high temperature, increasing the polymer chain’s radius of gyration R_g.