Hydroxyl-containing poly(amide imide)s (PAI-OH) in the molecular weight range from 44 to 146 kDa were studied by molecular hydrodynamics (viscometry) and light scattering in dilute solutions in N-methylpyrrolidone (N-MP). Scaling Mark–Kuhn–Houwink relationships were established, which made it possible to determine the key conformational parameters of the macromolecules. It was shown that in the studied molecular weight range, the PAI-OH macromolecule in N-MP should be considered as a relatively semi-rigid chain. The Kuhn segment length was determined to be 25±1 Å. Based on the obtained data, a calibration equation was derived that allows rapid estimation of the molecular weight of membrane-forming PAI-OH samples (Mw > 40 kDa) from viscometry data. The results of this work are important for predicting the properties of polymer materials and membranes based on hydroxyl-containing poly(amide imide)s.
Zakharova et al. (Tue,) studied this question.