Integral equation theory is applied to a coarse-grained model of water to study potential of mean force between hydrophobic solutes. Theory is shown to be in good agreement with the available simulation data for methane-methane and fullerene-fulleren
e potential of mean force in water; the potential of mean force is also decomposed into its entropic and enthalpic contributions. Mode coupling theory is employed to compute self-diffusion coefficient of water, as well as diffusion coefficient of a dilute hydrophobic solute; good agreement with molecular dynamics simulation results is found.
A self-consistent field theory study of lock and key type interactions between sterically stabilized colloids in polymer solution is performed. Both the key particle and the lock cavity are assumed to have cylindrical shape, and their surfaces are un
iformly grafted with polymer chains. The lock-key potential of mean force is computed for various model parameters, such as length of free and grafted chains, lock and key size matching, free chain volume fraction, grafting density, and various enthalpic interactions present in the system. The lock-key interaction is found to be highly tunable, which is important in the rapidly developing field of particle self-assembly.
We present a theoretical study of transport properties of a liquid comprised of particles uist1:/home/sokrates/egorov/oldhome/Pap41/Submit > m abs.tex We present a theoretical study of transport properties of a liquid comprised of particles interacti
ng via Gaussian Core pair potential. Shear viscosity and self-diffusion coefficient are computed on the basis of the mode-coupling theory, with required structural input obtained from integral equation theory. Both self-diffusion coefficient and viscosity display anomalous density dependence, with diffusivity increasing and viscosity decreasing with density within a particular density range along several isotherms below a certain temperature. Our theoretical results for both transport coefficients are in good agreement with the simulation data.
The absorption of free linear chains in a polymer brush was studied with respect to chain size $L$ and compatibility $chi$ with the brush by means of Monte Carlo (MC) simulations and Density Functional Theory (DFT) / Self-Consistent Field Theory (SCF
T) at both moderate, $sigma_g = 0.25$, and high, $sigma_g = 1.00$, grafting densities using a bead-spring model. Different concentrations of the free chains $0.0625 le phi_o le 0.375$ are examined. Contrary to the case of $chi = 0$ when all species are almost completely ejected by the polymer brush irrespective of their length $L$, for $chi < 0$ we find that the degree of absorption (absorbed amount) $Gamma(L)$ undergoes a sharp crossover from weak to strong ($approx 100%$) absorption, discriminating between oligomers, $1le Lle 8$, and longer chains. For a moderately dense brush, $sigma_g = 0.25$, the longer species, $L > 8$, populate predominantly the deep inner part of the brush whereas in a dense brush $sigma_g = 1.00$ they penetrate into the fluffy tail of the dense brush only. Gyration radius $R_g$ and end-to-end distance $R_e$ of absorbed chains thereby scale with length $L$ as free polymers in the bulk. Using both MC and DFT/SCFT methods for brushes of different chain length $32 le N le 256$, we demonstrate the existence of unique {em critical} value of compatibility $chi = chi^{c}<0$. For $chi^{c}(phi_o)$ the energy of free chains attains the {em same} value, irrespective of length $L$ whereas the entropy of free chain displays a pronounced minimum. At $chi^{c}$ all density profiles of absorbing chains with different $L$ intersect at the same distance from the grafting plane. The penetration/expulsion kinetics of free chains into the polymer brush after an instantaneous change in their compatibility $chi$ displays a rather rich behavior. We find three distinct regimes of penetration kinetics of free chains regarding the length $L$: I ($1le Lle 8$), II ($8 le L le N$), and III ($L > N$), in which the time of absorption $tau$ grows with $L$ at a different rate. During the initial stages of penetration into the brush one observes a power-law increase of $Gamma propto t^alpha$ with power $alpha propto -ln phi_o$ whereby penetration of the free chains into the brush gets {em slower} as their concentration rises.
