Facially amphiphilic phenylene ethynylenes

Facially amphiphilic poly(phenylene ethynylenes) were synthesized with various non-polar alkyl and polar amine side chains by Sonogashira-Hagihara coupling conditions. para-Phenylene ethynylene derivatives with pentoxy and tertiary amine side chains were dissolved in organic solvent, such as toluene or 1,2,4-trichlorobenzene, and introduced into an acidic, aqueous environment. The polymer molecules were found to self-assemble and stabilize these oil-water interfaces as visualized by confocal scanning laser microscopy. meta Derivatives containing dodecyl and primary amine side chains were also prepared and found to be active at the air-water interface. When analyzed by Langmuir trough experiments, this polymer was found to have an area of approximately 45 angstrom(2) per repeat unit, which correlates to an edge-on orientation at the air-water interface where the polar groups are immersed in the water sub-phase and both the hydrocarbon backbone and dodecyl chains extend away from the interface. Due to the facially amphiphilic architecture and large hydrocarbon side chains, these polymers were found to self-assemble from aqueous solutions into large aggregates with some order. Copyright (c) 2005 John Wiley & Sons, Ltd.