Confining Effects on Semiflexible Polymers in Hollow Particles

ABSTRACT 3D entrapment of polymers in nanocavities is crucial for a variety of synthetic and biomimetic materials, including hollow particles. We evaluate the effect of chain stiffness on the properties of polymers entrapped in cavities/capsules using molecular simulation. Two confinement‐induced phenomena are found to control the polymer distribution ρ ( r ) across the closed sphere. The near‐wall entropic depletion, characteristic of flexible polymers, manifests itself in monotonous profiles similar to those around a solid sphere in open systems. Contrarily, in moderately stiff polymers, the confining surface generates distinct density enrichment in profiles due to the development of toroidal conformations. The energetics of toroidal growth in a semidilute solution is quantified by simulation. The computed bending energy confirms a simpler generation of toroids in short polymers. The observed reduction of the persistence length in a cavity facilitates the growth of toroids. The thickness of the depletion layer determined by the novel universal method is in agreement with the data from the restricted conventional method. A close relationship is demonstrated between the concentration changes in the depletion thickness and the radius of gyration. The relevance of the computed confinement effects to bioanalytical or biomedical applications of capsules/hollow particles is discussed.