Are there (or can there exist) a room-temperature superfluid that is not toxic or in other ways dangerous to humans? (A superfluid being a liquid that can crawl up the sides of objects and completely cover it.)
I think it would be an interesting concept, as if a lake is mostly filled with it, boats could not cross it or they would quickly fill up with fluid and sink.
No.
The specific aspect you are looking at is zero viscosity while still having some surface tension.
As in the case of superconductors where something that doesn’t use BCS was a surprise, you still have the normal thermal motion of the particles getting in the way of the effects you desire.
So even with surprising metamaterials, under normal room pressure, you will still need ultracold temperatures to exhibit the superfluid film flow.
You might cheat a bit: say the unit wasn’t a large molecule but a very tiny grain of metamaterial or even a nanobot. It might show technical zero viscosity but still dampened out by random thermal motion; and the film creep doesn’t get very hight unless you shake the container, but once coated it stays that way.
There are no known room temperature superfluids. So, finding non-toxic room temperature superfluids is easy. They're part of a null set of a null set. Nothing easier.
All known superfluids exist at temperatures close to absolute zero degrees Kelvin. Absolutely not, at room temperature.
JDlugosz has made the interesting suggestion that certain metamaterials might exhibit superfluid properties like zero viscosity. Metaliquids like this, are in the correct sense, metaphysics in that they belong to physics beyond the physics we know (this is the definition of metaphysics). :)
