Supramolecular associations of poly(ketanil)s with sulfonic acid derivatives of benzenetricarboxamide via Brönsted acid-base interactions: Preparation, spectroscopic morphological and thermal investigations

Supramolecular aggregations have been obtained via ionic self-assembly of conjugated poly(ketanil)s and sulfonic acid derivatives of benzenetricarboxamides. To achieve this goal a new protonating molecule has been synthesized which is a derivative of 1,3,5-benzenetricarboxamide with sulfonic acid group at each of its ends. 1,3,5-benzenetricarboxamides of C3 symmetry tend to form ordered supramolecular aggregations via π-stacking and this property is retained in their sulfonic acid derivative. Because of their Brönsted acid nature the new molecules can additionally associate conjugated polymers with basic centers such as poly(ketanil)s. Depending on the processing solvent used (MC or DMA) 1,3,5- the sulfonic acid derivative of benzenetricarboxamide and its associations with poly(ketanil)s form aggregations of spherullite-like or feather-like morphologies as evidenced by polarized optical microscopy and atomic force microscopy. The similarity of this supramolecular organization is also corroborated by DSC studies which in both cases show endothermic type transitions of the same origin. The supramolecular acid-base associations are semi-crystalline in nature and exhibit good mechanical properties at room temperature because of a rather low Tg, in the vicinity of 300 K. This unusual lowering of Tg by ca. 90 K as compared to the case of poly(ketanil)s in their basic form is caused by the plasticizing effect of the protonating agent. Finally polyketanil-1,3,5-benzenetricarboxamide sulfonic acid derivatives show tunable photoluminescence which depends on the solvent and SO3H/CN molar ratio.