Geckos use the van der Waal force to stick to things, an effect that humans can replicate and make various materials that utilize such (like extra sticky gloves). My question is, would these work in a vacuum or near vacuum, as in space. The reason being I wish to use these instead of magnetic boots for astronauts as the latter only works on ferromagnetic material.
Geckos can stick to surfaces because their toes are covered in hundreds of tiny microscopic hairs called setae, each seta splits off into hundreds of even smaller bristles called spatulae. So they aren't actually sticky, they use the electromagnetic force from the electron on these hairs touching the electron from the surface. A scientist in germany in 1939 even showed this works when all the air is sucked out of a chamber with geckos inside. It is there for plausible to have this force work in space.
-Not an actual scientist, this is just what I compiled from many sources
Geckos, as Chebi Kitty explains below, stick to walls using the Setae and Spatulae to maximize the effect the Van der Waals force can achieve, and this is not dependent on an atmosphere so it does work in space...
I'm going to call Van der Waals Force VDW as its just easier
VDW force is very very weak, Geckos weigh very little and have large feet for an animal of their size. so something as large as a human then this force wouldn't be enough to hold them upside down.
Now obviously in space you would be in Zero G and therefore the VDW force would be enough if the astronaut was standing still, but the forces/momentum a human can generate would be difficult to compensate for using VDW alone. Geckos tend not to move very fast when on a vertical surface and even slower when upside down, and they don't carry a lot of momentum when they try and stop due to their very low mass with friction playing its part as well as VDW.
So while VDW Force may work it also probably wouldn't be strong enough to be the primary adhesive force for space boots, but may work well as a backup.