Verónica Calderón, Gert Schwarz, Félix García, María J. Tapia, Artur J. M. Valente, Hugh D. Burrows and José Miguel García
The synthesis and standard properties of polyisophthalamides with pendant benzo-X-crown-Y (X,Y = 12,4, 15,5, or 18,6) and their dipodal counterparts are described and correlated with the chemical structure (the thermal and mechanical properties, water uptake, and solubility). Polymerization under standard conditions yields insoluble gels, and a procedure to disregard gel formation is described. Furthermore, a plausible explanation accounting for such behavior is discussed in terms of cyclic oligoamide formation (Kricheldorf's kinetically controlled step growth polymerization) and subsequent threading with a growing polyamide chain to yield rotaxanes, catenanes, and polycatenanes. Moreover, to get insight into the polymer microstructures, films obtained by casting have been studied with wide-angle X-ray scattering, scanning electron microscopy, and hydrochloric acid transport studies through dense membranes.