Zur molekularen Dynamik der Lösungsprozesse von Polystyrol in verdünnten Lösungen

Abstract

AbstractRelaxation times for the dissolution processes of polystyrene are determined by light scattering investigations. Characteristic frequency numbers of rotation diffusion and torsion oscillations of the solvent molecules are determined from the Rayleigh‐wings. A correlation is found between the relaxation times τt,k0 of the 3rd stage of the dissolution process of polystyrene in different solvents and the frequency numbers δ2 of the torsion oscillations of the solvent molecules. Hence, amongst the two kinds of molecular motion of the solvent molecules, torsion oscillations are effective in the dissolution process of the solute and their frequencies have to be considered as dynamically effective. Evaluation of solvents based on these considerations does not correspond to the hitherto used rules which solvents are thermodynamically good ones and which solvents are poor ones. As an example chloroform exhibits for polystyrene the shortest relaxation time of dissolution and therefore is considered to be amongst the best solvents whereas benzene with its long relaxation time would be considered to be a poor solvent for polystyrene.