Macromolecular Theory and Simulations

Cover: Polymers may contain several active, dead, and dormant radical centers at the same time, which results in a multidimensional modeling problem. A model of the network formation kinetics during the nitroxide-mediated radical copolymerization of vinyl/divinyl monomers is presented in this work using a multifunctional macromolecule approach. The predictions of this model are then compared with experimental data. Further details can be found in the article by J. C. Hernández-Ortiz, E. Vivaldo-Lima,* and A. Penlidis on page 302.

Azobenzene liquid-crystal polymer films undergo significant light-induced deformation as a function of wavelength and polarization of light. This unusual liquid-crystal coupling with a polymer network is caused by light-stimulated microstructure evolution that is not well understood. A phase field modeling framework is developed to explain the complex multi-physics phenomenon.

A model for the nitroxide-mediated radical copolymerization kinetics of vinyl/divinyl monomers using a multifunctional macromolecule approach is presented. Polymer species are allowed to hold several active, dead, and dormant radical centers at the same time, which results in a multidimensional problem. Model predictions are compared against experimental data in order to validate the model.

A new method based on directed diffusion is presented for the preparation of atomistic models of crosslinked epoxy. This method enables the creation of crosslinked epoxy structures at high conversion (≈99%) while minimizing the use of code customization. The thermal and volumetric properties of the prepared model structures show good agreement with experimental data.

The structure of polyelectrolyte complexes consisting of two identical but oppositely charged macroions depends crucially on the stiffness of the macroions. Stiff chains form a “ladder” structure with parallel chains and almost all monomeric units assembling into ionic pairs. Complexes of flexible chains are globular structures with disordered positions of monomer units (referred to as scrambled eggs).

An axial dispersion model is used to predict the extent of transreactions (X) and degree of randomness (RD) in a series of PET/PEN blends melt mixed under varying blend compositions, mixing times and temperatures in a twin-screw extruder. The experimental and theoretical analyses show that the ADM model can be exploited to describe the effects of processing parameters on X and RD values.