Star polymers confined in a nanoslit: a simulation test of scaling and self-consistent field theories

Abstract

The free energy cost of confining a star polymer where f flexible polymer chains containing N monomeric units are tethered to a central unit in a slit with two parallel repulsive walls a distance D apart is considered, for good solvent conditions. Also the parallel and perpendicular components of the gyration radius of the star polymer, and the monomer density profile across the slit are obtained. Theoretical descriptions via Flory theory and scaling treatments are outlined, and compared to numerical self-consistent field calculations (applying the Scheutjens-Fleer lattice theory) and to Molecular Dynamics results for a bead-spring model. It is shown that Flory theory and self-consistent field (SCF) theory yield the correct scaling of the parallel linear dimension of the star with N , f and D, but cannot be used for estimating the free energy cost reliably. We demonstrate that the same problem occurs already for the confinement of chains in cylindrical tubes. We also briefly discuss the problem of a free or grafted star polymer interacting with a single wall, and show that the dependence of confining force on the functionality of the star is different for a star confined in a nanoslit and a star interacting with a single wall, which is due to the absence of a symmetry plane in the latter case.

Elasticity of polymeric nanocolloidal particles

“…The main parameters of the SPB are the number of chains f and the number of monomers per chain N c ; colloid diameter is where is the monomer diameter. Like in a related study 46 , steric monomer-monomer and monomer-colloid interaction is described by the Weeks-Chandler-Andersen (WCA) repulsion 47 and the bonds are modelled by the finite extensible nonlinear elastic (FENE) potential tuned such that the bonds do not cross. Our implicit-solvent scheme and this particular choice of interactions are both consistent with the good solvent conditions studied here.…”

“…The self-consistent field (SCF) theory was implemented on a cubic lattice using the Scheutjens-Fleer scheme 46 50 . We chose to represent the walls by a hard rather than Yukawa potential like in MD simulation.…”

Interface-enforced complexation between copolymer blocks

“…28 Recent simulations on polymers in confined space have not addressed intramolecular polymer complexation. [29][30][31]51 Hence, simulations are regarded within this manuscript to understand the interfacial properties of PPO-b-PDMAEMA.…”

Variable Chain Confinement in Polymers With Nanosized Pores and Its Impact on Instability

“…As deformation progresses, the constraint of a chain and therefore its tube diameter deforms from the motion of surrounding chains. It should be addressed that we use Flory-type free energy to build our model, which can be further improved by incorporating blob concepts [22]. As in classical continuum mechanics, let us consider a body Ω 0 with its boundary ∂Ω 0 .…”