Supramolecular Assemblies of a Semirigid Polyanionin Aqueous Solutions.

Inthis article, we report the supramolecular assemblies of a semirigidpolyelectrolyte, poly(2,2′-disulfonyl-4,4′-benzidineterephthalamide) (PBDT) in water. Cryo-TEM observation and SAXS measurementreveal that PBDT forms bundle-like structure even in very dilute concentration, CP, of 0.02 wt %. These bundle-like assembliesserve as new primary building blocks and self-assemble further as CPincreases, to form large associations withor without long-range orientation. When 2 wt % < CP< 6 wt %, liquid–liquid phase separation occurs.Some of the supramolecular associations form bipolar liquid crystalline(LC) droplets via a typical nucleation and growth process. The dropletsgrow up by the coalescence of small ones and sediment under the gravityand coalesce to form a bottom nematic phase. When CP≥ 6 wt %, the solutions are in a uniform nematicphase. The existence of these preliminary supramolecular assembliesof PBDT in aqueous solutions should be crucial for the formation ofnematic LC phase at a significantly low CP, as well as the formation of macroscopic ordered structures in hydrogelsvia electrostatic interaction between PBDT and oppositely charge multivalentmetallic ion or polycation. [ABSTRACT FROM AUTHOR]