Influence of the Type of Precipitant on the Structure of Phase-inversion Polyamido-imide Membranes

Porous phase-inversion membranes of complex morphology were obtained on the basis of aromatic polyamidoimides with different numbers of hydroxyl groups in the diamine component of the repeating unit. The influence of the quality of the precipitant (nonsolvent) applied in membrane preparation (i.e., the use of “strong” or “weak” nonsolvent) on structural and morphological features of polymer membranes of various chemical compositions was studied. Investigation of dilute solutions of membrane-forming polymers by optical methods revealed the changes in the state of the system both in the presence of a solvent and in the presence of a nonsolvent. On the basis of the obtained results, it was possible to estimate the sensitivity of the studied polymer/solvent/nonsolvent system to changes in the copolymer composition (a number of hydroxyl groups in the repeating unit).