Conformational characteristics in solution of molecules of polypyromellitimides based on 4,4′-diaminodiphenyl, 4,4″-diaminoterphenyl and 2,5-DI-(p-aminophenyl)pyrimidine

Abstract In solutions of 101% sulphuric acid the authors have studied the dependences of the optical shear coefficient [n]/[ν] on the intrinsic viscosity [ν] for three polypyromellitimides based on the diamines: 2,5-di( p -phenyl)pyrimidine (PMI-I), terphenyl (PMI-II) and benzidine (PMI-III). They determine the limiting, Gaussian values ([n]/[ ν ]) ∞ equal to (3000 ± 200) × 10 −10 g −1 cm s 2 for PMI-I and 10 −10 for PMI-II and PMI-III. For optical anisotropy per unit chain length equal to (22 ± 2) × 10 −17 cm 3 the authors calculate the lengths of the Kuhn segments A I = (1750 ± 250) × 10 −8 and A II = A III = (625 ± 125) ×(1075 ± 125) ×10 −8 cm to which correspond the following numbers of monomer units: S I = 83 ± 12; S II = 30 ± 7 and S III = 37 ± 7. The values found are interpreted in terms of the defectiveness of the structure of the chains.