Density Functional Theory of Polymer Structure and Conformations

Abstract

Abstract:We present a density functional approach to quantitatively evaluate the microscopic conformations of polymer chains with consideration of the effects of chain stiffness, polymer concentration, and short chain molecules. For polystyrene (PS), poly(ethylene oxide) (PEO), and poly(methyl methacrylate) (PMMA) melts with low-polymerization degree, as chain length increases, they display different stretching ratios and show non-universal scaling exponents due to their different chain stiffnesses. In good solvent, increase of PS concentration induces the decline of gyration radius. For PS blends containing short (m 1 " 1´100) and long (m " 100) chains, the expansion of long chains becomes unobvious once m 1 is larger than 40, which is also different to the scaling properties of ideal chain blends.

Depletion Interactions between Nanoparticles: The Effect of the Polymeric Depletant Stiffness

“…The radius of gyration for our microscopic model of the semiflexible chain specified in Section 2 is calculated using the DFT methodology described in detail in Ref. [44] (with the Helmholtz free energy functional and the weighted density defined in Section 3). All the results reported below were obtained for the value R g = 10 and the following five pairs of values of N and κ: (N = 40, κ = 25.1), (N = 48, κ = 11.5), (N = 64, κ = 6.2), (N = 80, κ = 4.4), and (N = 96, κ = 3.5).…”

Synthesis, Self-Assembly and In Vitro Cellular Uptake Kinetics of Nanosized Drug Carriers Based on Aggregates of Amphiphilic Oligomers of N-Vinyl-2-pyrrolidone

“…Interestingly, the linear dependence of the free energy of solvation of PVP-OD on the molecular weight of the hydrophilic fragment can only be observed for small 𝑀 ̅ 𝑛 , when the contribution of interactions between N-vinyl-2-pyrrolidone residues to the free energy of dissolution remains rather constant. For large 𝑀 ̅ 𝑛 , on the other hand, when the density of hydrophilic units inside the polymer coil increases [38] and the contribution of poly mer-solvent interactions drops, deviations from the linear dependence are observed. The latter presumable also leads to a break in the linearity of the ln(CAC) dependence 𝑀 ̅ 𝑛 when the number average molecular weight exceeding 20 kDa.…”