Adsorption of active polymers on attractive nanoparticles

The adsorption of active polymers on an attractive nanoparticle (NP) is studied using Langevin dynamics simulations. The active polymers consist of an active Brownian particle (ABP) at the head and a subsequent passive polymer chain. The ABP experiences an active force of magnitude Fa. The interactions between the active polymer and NP are modeled as Lennard-Jones potential with a strength epsilon pn. We find the critical adsorption point epsilon pn* increases with increasing the active force Fa. The increment of epsilon pn*, denoted as Delta epsilon pn*, due to Fa can be expressed approximately as Delta epsilon pn* proportional to Fa2.5 for the restricted rotating active polymer (RRAP) where the rotation of the head ABP is restricted and Delta epsilon pn* proportional to Fa1.7 for the freely rotating active polymer (FRAP) where the ABP rotates freely. Meanwhile, the conformation of the adsorbed polymer, such as adsorbed trains on NP and the tail near the ABP, are also dependent on Fa. When the tail near the ABP is short, the adsorption is significantly affected by the active force. However, when the tail is long, the whole polymer can be viewed as a long tail stretched by the active force and unperturbed adsorption monomers. Simulation results show that the active force has a direct and significant effect on epsilon pn* and the structure of the adsorbed active polymers. The critical attraction strength for the adsorption of active polymers on nanoparticles increases with the active force. It becomes more sensitive to the length of the polymers under the action of active force.