Structural transformations during chemical modification of the surface of the film of polypyromellitimide

Using electron microscopy data, the formation of a submicron layer of polyamide acid (PAAc) on the surface of the polyiromellitimide (PI) film was studied when PI was successively treated with aqueous solutions of alkali and acid. To analyze the topology of the distribution of clusters of PAAc macromolecules on the surface of samples of modified PI film, the method of decorating PAAc with silver chloride nanoparticles was applied. The spatial distribution of the density of ensembles of decorating nanoparticles was found to be ordered. It is shown that the degree of order changes non-monotonically with increasing time of alkaline hydrolysis of PI. This change is explained by the superposition of two processes: the formation of PAAc clusters as a result of a topochemical reaction in the chains of PI macromolecules and random cluster-cluster aggregation. The centers of formation of PAAc clusters are periodically alternating microdomains – dense aggregates of PI macromolecules. The modes of obtaining an ordered PAAc cluster structure when modifying the PI surface are set.