Molecular shape transitions driven by an external force: the case of polymer chains with transient knotted loops

摘要: We study the simulated relaxation behaviour of grafted polyethylene with transient topological constraints. employ a “soft” steered molecular dynamics algorithm, whereby chain stress is introduced by sequence stretchings/compressions at free (nongrafted) end chain. Each bond perturbation allowed to dissipate within using constrained dynamics, before next applied. Using knotted-loop as model for entanglement, we show occurrence range shape transitions that are not visible in mean size. During stretching phase, formation rigid and tight knotted loops can be recognized variation entanglement complexity or local compactness. due removed reversibly during compression eliciting delocalization even very knots. also find knot still marginally diffusive along whenever external couples torsions.