| Molecular dynamics simulations are employed to investigate the dielectric behavior of polar macromolecules in different environments. Simulation conditions are designed to explore systems of polymers tethered by their one end on impermeable surfaces and systems of homogeneous solutions. An effort is made to compare the theoretical results with dielectric spectroscopy experimental observations. There are issues unresolved by experiments and unreconciled by prevailing theoretical treatments. Simulations are an effective means for exploring the behavior of physical systems at a microscopic level, and in this work we hope to provide insight into the molecular mechanisms of phenomena observed by dielectric spectroscopy experiments.;Initially, polar polymer brushes, i.e. end-grafted polymeric chains, are treated. The structural properties are investigated as a function of the monomeric dipole moments. Dielectric loss curves are calculated from the transient response of the systems, when external electric fields are applied. The roles of the spatial confinement and the thermodynamic confinement (to keep uniform segment density) on the distribution of relaxation modes are clarified. The response of the polar brushes is, in addition, related to the equilibrium fluctuations of the chains' end-to-end vector.;Next, we examine the dielectric behavior of homogeneous solutions of polymers at concentrations varying from infinite dilution to the melt concentration. The solvent quality is varied and the structural properties are calculated as a function of the chain size and the concentration. The dielectric relaxation of the macromolecules is investigated using both equilibrium and non-equilibrium simulations, applying external electric fields. Comparing the simulation results to experimental dielectric spectra, we propose a mapping of the model parameters to real polymer properties.;The simulations are computationally very demanding and a parallel time decomposition scheme is described in the last part of the thesis. |
