Polymer chains in a soft nanotube: A Monte Carlo Study

Abstract

We study the equilibrium properties of flexible polymer chains confined in a soft tube by means of extensive Monte Carlo simulations. The tube wall is that of a single sheet six-coordinated self-avoiding tethered membrane. Our study assumes that there is no adsorption of the chain on the wall. By varying the length N of the polymer and the tube diameter D we examine the variation of the polymer gyration radius Rg and diffusion coefficient Ddiff in soft and rigid tubes of identical diameter and compare them to scaling theory predictions. We find that the swollen region of the soft tube surrounding the chain exhibits a cigarlike cylindrical shape for sufficiently narrow tubes with D<<Rg. The observed scaling of static conformational properties with chain length N and tube diameter D follows the predictions of scaling theory and displays no significant difference between soft and rigid tubes. The Brownian dynamics of the polymer diffusion in a rigid tube is found to slow down in a tube with soft walls by an amount which depends on the Rg/D ratio albeit the relaxation time tau(parallel) for diffusive motion along the tube still scales as tau(parallel) proportional, N3.

Swollen-to-Globular Transition of a Self-Avoiding Polymer Confined in a Soft Tube

“…[12] seems to support this prediction, however, a study based on Monte Carlo simulations has failed to observe the globular phase [13]. In this work, using Monte Carlo simulations, I demonstrate that a globular phase can be stabilized in a certain regime of the parameter space, qualitatively verifying the prediction of Ref.…”

“…Furthermore, the success of making the approximation, which ignores the angular-dependent fluctuations (which is not a main factor in the swollen-to-globular transition) of the soft tube, enables the computer simulations of large systems needed for the observation of the transition. In contrast, Monte Carlo simulations in a related study were performed on a model containing a two-dimensional network of nodes representing a fluctuating surface [13], which could not be numerically pushed far enough for simulating large systems.…”

Adsorption of block copolymers in nanoporous alumina

“…Flexible polymer chains end‐attached to a surface in good solvent tend to extend away from the surface at sufficiently high grafting density, as a result of excluded volume interactions, to form a layer of stretched chains known as a “polymer brush.” Such systems have been the subject of extensive theoretical and experimental studies1 due to their various applications in colloidal stabilization, adhesion, wetting, and lubrication as well as tailoring surface properties and the development of responsive nanomaterials 2. In recent years, the properties of polymer brushes formed on convex or concave interfaces have been studied using theory or simulation 3–15. Scaling theory,3–7 Monte Carlo,7–12 and molecular dynamics simulations13, 14 have been used for this purpose.…”

Motion of Star-Branched Chains in a Nanochannel. A Monte Carlo Study

“…The short-and long-time dynamics, orientation and deformation of coils and instantaneous shape of the confined chains were also determined. The confinement theoretical treatment of a polymer chain in a tube was also a subject of interest for computer simulations [12][13][14][15][16][17] and theoretical considerations [18][19][20]. The structure of the chain compressed in a narrow tube (narrow means that the diameter of the tube is smaller than the diameter of the polymer chain at good solvent conditions) was determined and compared to that of chains in a bulk solution.…”