Conformational properties of flexible polymer chains in highly confined environments

Abstract

In this work we describe a detailed study of the conformational properties of flexible polymer chains confined into rigid wall spherical cavities of different sizes, with dimensions comparable to those of the chains. An off-lattice Monte Carlo algorithm has been used to simulate the behavior of excluded-volume, freely jointed chains in a wide range of concentrations. The considered properties include the size and shape of the chains, different densities of the system, and the orientation of certain characteristic vectors. All these properties are analyzed as a function of the position in the spherical cavity, trying to determine how each property is affected by the presence of the spherical rigid wall. A comparison with the results found in the literature for polymer systems confined between infinite parallel plates is done whenever possible, with some significant differences.

Conformation of Chains in Cores of Block Copolymer Micelles with Solubilized Homopolymer: a Monte Carlo Study

“…The solubilized chains close to the core center almost do not feel the spherical confinement and are fairly random in their orientation, as it was shown in ref. [65] Systems with Different Fractions of Tethered and Solubilized Chains of the Same Length For all systems differing in the fraction of solubilized and tethered chains, the densities of the gravity centers (Figure 6) are qualitatively the same as in the previous case. However, in the system with a high fraction of tethered chains, the solubilized chains are expelled from the subsurfacial layer since the tethered chains form a somewhat denser brush.…”

“…The density of gravity centers of solubilized chains reaches a maximum at the same distance from the surface (the chains have the same lengths), but, in contrast to tethered chains, it remains almost constant for lower radial distances. Free chains in the system studied by Jorge and Rey [65] show the same behavior.…”

“…These results are consistent with the data of Jorge and Rey. [65] In their detailed study they also found that chains close to the surface are more compressed than those in the center. Their shape is, however, independent of the radial distance.…”

“…[65] They studied self-avoiding chains by off-lattice Monte Carlo simulations. (A similar but simpler system of intersecting chains enclosed in a spherical cavity was also studied by Dayantis and Sturm [66] ).…”

“…In contrast, the density in the system studied by Jorge and Rey is not constant. [65] It is zero in the vicinity of the surface (for distances smaller than the radius of a chain bead in their model, r. It sharply increases at the distance d = r and then oscillates around the average segment density. This type of behavior is well-known in the theory of simple fluids.…”