ABSTRACT
The chemical structures of aromatic polyimides and their derivatives, polyamideimides, polyesterimides, and polyesteramideimides, are very varied, which corresponds to a great diversity in their physical properties. Polyesteramideimides are the polymers intermediate in chemical structure between polyesterimides and polyamideimides. This chapter considers the different phase states of polyimides in bulk: amorphous, mesomorphic, quasicrystalline, and crystalline. It discusses the correlations between the supermolecular structure and some properties of polyimides and their derivatives. The chapter explores new data on the crystalline structure of rigid-chain polypyromellitimides and the mesomorphic structure of polyimides containing joints in the monomer unit. It also considers the molecular and supermolecular structures of different copolyimides and of polyimide mixtures. The chapter proposes a model for the supermolecular structure of rigid-chain polyimide films. Polyimides with different chain flexibilities and crystallizabilities yield blends with a limited compatibility of the components.
