ABSTRACT
Reliable data on the properties of individual macromolecules can be obtained only when they do not interact with each other that is they are separated from one another. There are many experimental techniques for investigating macromolecules in solvents and many theories about how to interpret the results of these investigations. Experimental investigations of polyamic acid and polyimide macromolecules in dilute solutions are conducted mainly with molecular hydrodynamics and molecular optics as well as with other highly informative techniques. This chapter discusses some examples of the application of described methods for the estimation of the macromolecule rigidity of specific polyamic acids and polyimides. Polyamic acid molecular weight usually decreases during storage of its solutions. The formation of ordered supermolecular structures in polyamic acid solutions is frequently related to the presence of carboxylic and amide groups in polyamic acid chains and the occurrence of hydrogen bonds between them. The chapter also discusses the comparative data on polyamic acid and polyimide macromolecule rigidities.
