Macromolecular Theory and Simulations

Cover: Complexes formed by a charged dendrimer and an oppositely charged chain with finite rigidity are studied using Monte Carlo simulations. As the rigidity of the chains is increased, the shapes of these chains undergo various transitions. In the limit of strong electrostatic couplings and high rigidity, long chains show a release of tails from the complex. Further details can be found in the article by J. S. Klos,* and J.-U. Sommer on page 448.

The loss modulus E″ in polymer networks stretched by a factor λ is theoretically studied. The range of λ under study ranges up to ultimate extension close to fracture. Consideration of the local chain structure distortion at very large network extensions causes appearance of a maximum on the strain dependence of the loss modulus.

MC simulations are used to study the properties of complexes formed by a charged dendrimer and an oppositely charged chain with finite rigidity. It is shown that at sufficiently low temperature such complexes are stable and accompanied by selectively condensed counterions irrespective of chain rigidity. The dependence of preferred chain conformations on chain rigidity is explored.

1,5-Hydrogen transfer reactions in methyl acrylate and butyl acrylate free-radical polymerization are studied using quantum chemistry and transition state theory to estimate the kinetic parameters with tetrameric radicals. A two-step transformation is found to account for the overall reaction.

The spontaneous polymerization of glycidol is an important side reaction in the synthesis of hyperbranched polyglycerol at elevated temperatures. Evidence is reported that indicates the importance of thermally induced ring-opening reactions in the polymerization of glycidol. The software PREDICI is used to estimate Arrhenius parameters for rate coefficients of thermal ring-opening reactions based on experiments conducted at different temperatures.

The probability of the chain conformations P(r) for a chain with a given end-to-end distance vector r is calculated via the chain entropy S(r), in contrast to another works where that probability is assumed to be equal to the probability p(r) of obtaining the distance r in a random-walk process. In general the probability P(r) in not equal to the probability p(r).

The translocation dynamics of bottle-brush polyelectrolytes (BPE) in an attractive channel is studied using molecular dynamics simulations. Varying the electric field can significantly affect axial and radial migration dynamics of the BPE. The BPE exhibits a stretching–shrinking migration along the channel direction at strong electric fields.