Extraction of a hydrophilic compound from water into liquid CO2 using dendritic surfactants

Dendrimers are well defined, highly branched polymers(1-5) that adopt a roughly spherical, globular shape in solution, Their cores are relatively loosely packed and can trap guest molecules(5-7), and by appropriate functionalization of the branch tips the macromolecules can act as unimolecular micelle-like entities(6). Here we show that dendrimers with a fluorinated shell are soluble in liquid carbon dioxide and can transport CO2-insoluble molecules into this solvent within their cores. Specifically, we demonstrate the extraction of a polar ionic dye, methyl orange, from water into CO2 using these fluorinated dendrimers. This observation suggests possible uses of such macromolecules for the remediation of contaminated water, the extraction of pharmaceutical products from fermentation vessels, the selective encapsulation of drugs for targeted delivery(6,7) and the transport of reagents for chemical reactions (such as polymerization(8-11)) in liquid and supercritical CO2 solvents.