Category: Color

This work aims at assessing the influence of two different solvents, bidistilled water and toluene, on dispersions of carbon-based engineered nanomaterials, namely, fullerenes, and their self-assembly behavior…. Aggregates obtained in toluene showed a well-formed crystal structure. When using water, the obtained aggregates were amorphous and showed a no well-defined shape. Their sizes ranged between 20 and 40 nm for nanosized structures and between 0.4 and 4.8 μm for micron-sized self-aggregates.

For starters, for the better part of two decades now, a purple color has been the standard for determining if a product contains C-60. A purple color!

C-60 turns purple when mixed with Olive oil. Just about everybody who manufactures this stuff makes that claim.

As it turns out, that purple color comes from residual toluene left over from the manufacturing process.

Yeah, you read that right. RESIDUAL TOLUENE! Or, residual amounts of other solvents such as benzene or xylene.

Pure, unadulterated C60 is BLACK. C60 is only ever “purple” (or “magenta”) when it has interacted with solvents such as Toluene. In other cases, it may be yellow, green, pink or brown, depending on which solvent is used (see Fig. 1). The color change in C60 in various solutions is the result of “solvation shells” which are formed between the solute (C60) and solvent when they interact. This interaction changes the electrophysical properties of the C60 molecules, causing them to aggregate (i.e., cluster) into crystal formations of various shapes and sizes. It is these crystal formations of aggregated C60 that reflect specific wavelengths of light and which result in “color”. Since the electrophysical properties of the C60 are permanently altered from having interacted with a solvent, C60 remains in an aggregated, crystallized state, even after the solvent has been vaporized off. Additionally, some solvent also remains behind, being both chemically bonded to and physically trapped within the C60 molecules. Hence, re-dissolving the solid C60 “powder” that is left behind after this process into an oil will still produce a color change. It is evidence of crystallized, aggregated C60 from solvent extraction methods.