Synthesis and association behavior in an aqueous media of amphiphilic alternating copolyimides having sulfonic acid group

We herein report the synthesis of amphiphilic alternating copolyimides (AACs) and their aggregation behavior in an aqueous system. AACs showed good solubility toward 20 mM Tris HC1 buffer (pH=7.0). The aggregate formation of AACs was confirmed through UV spectral study using pinacyanol chloride as a spectrophotomeric probe. In dynamic light scattering, AACs showed two distinct populations of the aggregated species. For smaller particles, the diameter was estimated to be 100-300 nm. In contrast, those of larger particles were 2-3 μm. Such an aggregate formation was not observed with the random copolyimide counterparts. It is worth mentioning that diameters of aggregates were much larger than those of known amphiphilic polymers.