Macromolecular Theory and Simulations

Cover: The water dynamics near polystyrene thin films with different degrees of hydrophilicity are investigated. The orientational autocorrelation function of the vector associated with the water dipole is calculated in each layer of water of 0.125nm thickness from the interface into the bulk region. Further details can be found in the article by S. A. Muntean,* R. A. Gerasimov, and A. V. Lyulin on page 544.

Contributions of low concentration species can be accurately modeled by small scale Monte Carlo simulations. A new, efficient method allows tracing species which can appear in modeled systems even for very short time intervals only. The figure shows the exact distribution of active radicals obtained from modeling of the controlled radical polymerization process.

The molecular mechanisms of energy transfer in ordered polymer systems such as polymer crystals are mostly determined by mobility of such elementary excitations as phonons, solitons, and breathers. We present for the first time both analytical and numerical study of the breathers in the spiral polymer chain in application to polytetrafluoroethylene crystal.

A computationally simple approach combining DFT and semiempirical method is proposed to estimate hardness and electrophilicity values of conductive polymers. A new two parameters exponential model is introduced for extrapolation of these electronic properties.

MD simulations are conducted to compute pressure and molecular-weight dependence of Hildebrand's solubility parameters of hexane and HDPE at high pressure and temperature. The effect of electrostatic potential energy contribution to cohesive energy and density is investigated. An analysis of the pair distribution function is carried out.

MD simulations for the dynamics of water near hydrophilic and hydrophobic polystyrene surfaces are presented. The quantities that characterize the dynamic behavior of water in the first layers near the interface are compared with those in bulk. The influence of the polystyrene model on the dynamic properties of water is studied.

For step-growth polymer systems of general type “AfiBgi”, a fast method is derived to compute the MSD and the MWD. The figure shows the full MWD curves of system “A1B1 + B1 + A2 + B3” with p_A[gel] = 0.969877 at p_A = 0.964, 0.967, 0.969. Blue: calculated using recurrence scheme. Red: calculated using analytic approximation.

The article presents the study of the coherent dynamic structure factor of a chain confined into harmonic radial potential. The theoretical framework allows one to investigate easily the crossover from constrained to unconstrained (Rouse-like) dynamics.