Molecular assemblies of amphiphilic oligothiophenes at the air-water interface

The engineering of conjugated oligo- and polymers at the micro- and nanoscale is crucial for developing advanced functional materials and electronic devices, such as OFETs, OLEDs, and sensors, due to their electronic and optoelectronic properties being highly dependent on their supramolecular order. This research investigates the self-assembly and aggregation behavior of a series of amphiphilic oligothiophenes with varying hydrophilic/hydrophobic balances, synthesized through palladium-catalyzed cross-coupling reactions. The molecular structures were characterized using NMR and mass spectrometry, and their optical properties were examined by UV-Visible absorption spectroscopy, revealing distinct absorption maxima influenced by the molecular architecture. Dynamic light scattering (DLS) and cryotransmission electron microscopy (cryo-TEM) studies demonstrated the formation of spherical aggregates with diameters around 200 nm in aqueous solutions, consistent with scattering measurements indicating low critical micelle concentrations (cmc). Adsorption isotherms and Brewster Angle Microscopy (BAM) highlighted the interfacial properties and interactions of these amphiphilic molecules at air/water interface, emphasizing the impact of their structural features on self-assembly and material properties. These findings underscore the potential of amphiphilic oligothiophenes in tuning solution self-assembly, morphology, and optoelectronic characteristics for applications in advanced electronic materials.