Structure of comblike polyimide prepolymer solutions

The viscometry and light scattering techniques and the Debye-Stein statistical theory were applied to study the structure of amphiphilic polyimide prepolymers and variation of the structure with time in a mixed dimethylacetamide-benzene solvent. The solutions of dimethylhexadecylamine salt of the poly(amic acid) based on 3,3',4,4'-biphenyltetracarboxylic dianhydride and o-tolidine were studied. These solutions are used for casting the Langmuir-Blodgett films. It was shown that, in going from the poly(amic acid) to its ammonium salt, the intrinsic viscosity and, therefore, the hydrodynamic sizes of a macromolecular coil decrease. In dilute solutions of the salt in a dimethylacetamide-benzene mixture, supramolecular associates of the fluctuation nature were revealed. On storage, these solutions undergo structural self-organization which is displayed as a considerable increase in the solution microheterogeneity and local ordering.