Headgroup effects on the krafft temperatures and self-assembly of ω-hydroxy and ω-carboxy hexadecyl quaternary ammonium bromide bolaform amphiphiles: Micelles versus molecular clusters?

► Eight asymmetric bolaform amphiphiles with different polar end-groups have been synthesized. ► All of the amphiphiles dissolved and aggregated in water above a given temperature. ► Aggregation temperature was dependent upon molecular structure and pH. ► The aggregates for the alcohol ammonium amphiphiles formed small classical micellar structures. ► The carboxylic acid ammonium amphiphiles formed larger and looser molecular clusters.