ABSTRACT
This chapter discusses the effect of solid polymeric medium structural features on the molecular mobility of additives. Polymers may be formed into a sequence due to their chemical structure. A definite growth of size of the side groups promotes an increase of molecules mobility. It causes a weakening of intermolecular interaction, an increase of free volume and intramolecular flexibility of the chain. The effect of branchings is similar to introduction of bulk side groups. Macromolecules with large number of branchings loose their capability for dense packing and crystallization. The chain flexibility grows with the introduction of recurrent double bonds. Rotational diffusion of additives obeys the same regularities that translational ones. Formation of cross links in a polymer due to chemical and physicochemical processes leads to a decrease in the rotational and translational dynamics of additives.
