Accuracy Limits of the Blob Model for a Flexible Polymer Confined Inside a Cylindrical Nano-Channel

چکیده مقاله

The blob model is a well-known scaling theory for polymers in confined environments. In this manuscript, the limitations of the blob model for a flexible polymer confined inside a nano-cylinder are clarified theoretically and using molecular dynamics simulations. In this model, the confined polymer is divided into smaller sections called blobs. The free energy of the confined polymer is accurate under the conditions that (1) the number of monomers inside each blob and (2) total number of the blobs is large enough. In simulations, we consider the opposite limit of extremely narrow nano-channels. Interestingly, the simulation results show that the theory can describe the statics of the confined polymer, even when the above two requirements are not satisfied. However, when simulation parameters are beyond the theoretical limits, the fluctuations in the radius of gyration of the confined polymer have a much stronger dependence on the diameter of the nano-channel than the blob model predicts.