Hybrid Density Functional Theory for Homopolymer Mixtures Confined in a Selective Nanoslit

Abstract

By integrating polymer density function theory (DFT) and single-chain molecular simulation, a hybrid DFT is developed for homopolymer mixtures confined in a selective nanoslit. Two weighting functions are adopted separately in the polymer DFT for repulsive and attractive contributions to the excess free energy functional. The theoretical results agree well with simulation data for the density profiles, configurations (tail, loop and train), adsorption amounts, layer thicknesses, and partition coefficients. The polymer-slit interaction is found to have a large effect on the density profiles and partition coefficients but is found to have a small effect on the average sizes and percentages of the configurations. Nearly half of the polymer segments form tails, and the other half form trains. In addition, bridges are observed to form for sufficiently long polymer chains. As the length difference between two polymers increases, the effect of chain connectivity becomes increasingly important.

Solvation effects for polymers at an interface: A hybrid self-consistent field–density functional theory approach

“…[40][41][42][43][44][45] The advantage of this approach is that practically all global and local properties of polymers at interfaces (such as center-of-mass profile or the end-to-end vector profile) can be fairly easy calculated and analyzed. [46][47][48] It is well known that the polymer coil changes its average size upon changing the polymer concentration. 49 For a polymer in the good solvent, the scaling theory says that size of the linear polymer of M segments, e.g., as measured by the gyration radius, R g , will shrink from R g ∼ M 0.56 in the dilute regime to R g ∼ M 0.5 in the concentrated regime.…”

Concentration Dependence of Size, Shape, and Orientation of Copolymers, 1 – Linear Diblock and 4‐arm Hetero Star Polymers

“…Provided that their volumes remain constant, centers and also centers of gravity are expected to near each other as the areal density on the interface decreases. As a further consequence, as the lamellar microphases obviously form a spatial confinement for the constituting arms, it is reasonable that all chain/star related properties evaluated are affected by d in the same way 70, 71…”

Description of fluid-tethered chains interfaces: advances in density functional theories and off-lattice computer simulations

“…Generally, the so-called DFT-SCFT approaches rely on a combination of computer simulations of a single chain in an effective position dependent field that results from nonlocal DFT [70][71][72][73][74][75]. The advantage of the DFT-SCFT approaches is that practically all global and local properties of polymers at interfaces, such as the center-of-mass profile or the end-to-end vector profile, can be calculated and analyzed [76][77][78][79]. In particular, those methods can be used to take into account the shrinking or the swelling polymers at the surface.…”