New Membrane-Forming Aromatic Co-Poly(amide-imide)s: Influence of the Chemical Structure on the Morphological, Thermal and Transport Properties

Polymer film membranes are used to solve specific separation problems that dictate structural requirements. Structural and morphological parameters of film membranes based on glassy polyheteroarylenes can be controlled in the process of preparation from solutions that opens up prospects for obtaining structured membranes required for targeted separation. In the case of aromatic poly(amide-imide)s, the possibility of controlling film formation and structure virtually has not been studied. In the present work, a series of homologous co-poly(amide-imide)s differing in the number of repeating units with carboxyl-substituted aromatic fragments was synthesized by polycondensation. Comparative analysis of the processes of formation of membranes with different morphologies based on these polymers under equal conditions was performed. New information was obtained about the influence of the amounts of carboxyl groups and the residual solvent on structural properties of asymmetric membranes. The influence of these factors on transport properties of dense membranes under pervaporation conditions was studied. It was demonstrated that in the case of carboxyl-containing poly(amide-imide)s, the domains formed during film preparation had a significant effect on membrane properties.

Antisite disorder and phase segregation in Mn2NiSn

A systematic study of crystal structure, local structure, magnetic and transport properties in quenched and temper annealed Ni2−xMn1+xSn alloys indicate the formation of Mn3Sn type structural defects caused by an antisite disorder between Mn and Sn occupying the Y and Z sublattices of X2YZ Heusler structure. The antisite disorder is caused by the substitution of Ni by Mn at the X sites. On temper annealing, these defects segregate and phase separate into L21 Heusler and D019 Mn3Sn type phases.