Gels are one of the rheological nightmares: not only are they more difficult to make measurements on, but even defining a gel is a unresolved issue. The great P.J. Flory, in his 1974 Introductory Lecture for the Faraday Discussions pretty much gave up on a literal definition and went with a working definition, breaking gels into 4 classes. One issue that he also mentions, but doesn't resolve is the need for 2-phases as was proposed by Hermans (oh it is so much fun to do such name dropping today!). Flory wasn't a fan of the 2-phase requirement as he thought vulcanized rubber, aerogels and other 1-phase materials should be considered gels too. While there hasn't ever been a clear resolution to the matter, the existence of 1-phase gels and their supporters are clearly in the minority. [*]
Regardless of the definition, there is a new report (open access) that C60, a.k.a. Buckyballs, are capable of forming a gel just by themselves. At least in a computer simulation that lasted only 100 ns. Still, this is something that should be looked into further - it should be relatively easy to do. Assuming the gel state can be verified, would it be good for anything? Given the track record for C60, probably not. But are there other materials out there for which a 1-phase gel state would be useful? That is the real question.
[*] Personally, I support the 2-phase concept. I'd call 1 the one-phase materials listed above as "gellable", but that is very much me. I am comfortable with whatever terms people are already using, except for those that use the term too broadly (a whole other subject).
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