Selective destruction in alkali solutions of imide and urethane blocks in thermolized samples of copoly(urethane-imide) films

The selective destruction of urethane and imide units in a copoly(urethane-imide) obtained on the basis of pyromellitic anhydride, 4,4′-oxydianiline, toluene-2,4-diisocyanate, polycaprolactone and containing an increased proportion of imide units was investigated. A sequential destruction was carried out, including preliminary thermolysis of the samples followed by hydrolysis of the film in solutions of potassium oxide hydrate. It is shown that in the process of chemodestruction, imide units are more labile compared to urethane units (based on polycaprolactone). As a result of chemodestruction, in the final samples, which are similar in chemical structure to poly(oxydiphenylene)pyromellitimide, urethane blocks remain in residual quantities. The characterization of the final films was carried out using the methods of TGA, DSC, DMA, AFM. The deformation-strength properties of the samples remain almost constant during the destruction processes of the copoly(urethane-imide). The results obtained are of interest in the light of the development of porous membrane materials.