Solubilization and Encapsulation of Fullerenes by Amphiphilic Block Copolymers

摘要

Solubilization and encapsulation of fullerenes C60 and C70 by ultralargehollow micelles formed by rod-coil diblock copolymers and characterization of the resulting self-organized fullerene-block copolymer assemblies are reported. The solubilization capacity of each fullerene in poly(phenylquinoline) -block-polystyrene (PPQ-PS) micelles in binary solvents, trifluoroacetic acid/dichloromethane and trifluoroacetic acid/toluene, was determined to be 200 mg fullerene per gram of PPQ-PS and found to be independent of block copolymer composition and concentration. This represents fullerene solubility enhancement by factors of 1040 and 63 compared to the solubilities in pure dichloromethane and toluene, respectively. Fullerenes C60 and C70 were found to change the micellization and self-assembly of PPQ-PS blockcopolymers in solution from polymorphic aggregates to only hollow spheres with encapsulated fullerenes. The solubilization and encapsulation of up to 1 - 10 billion fullerene molecules in PPQ-PS block copolymer micelles increased the aggregation number to over 10 to the 9th power while the aggregate diameter increased from 1-5 microns toover 30 microns. Photoluminescence emission and excitation spectra of the fullerene-PPQ-PS block copolymer assemblies evidenced fullerene-induced J-aggregation of the conjugated PPQ blocks. In addition to providing the first detailed knowledge of the effects of solubilizates on the molecular packing of block copolymer micelles, the self-organized fullerene-block copolymer assemblies constitute novel mesoscopic supramolecular materials for electronic, optoelectronic, photonic and other applications. These results also provide evidence of micellization and micellar solubilization phenomena at the 1 to 30 micrometer size scale.