Not sure what is used today, but when Unobtanium was first filed for patent for the nose piece and along the earstem, it stated this:
“In a particularly preferred embodiment, the traction member 40 is formed of a relatively soft elastomeric material having a coefficient of sliding friction that increases when the material is wetted. Such a material, sometimes referred to as hydrophilic, tends to enhance retention of the traction member 40 in position on the wearer's head as the wearer perspires or encounters moisture, as during skiing.
One suitable material which can be readily molded by conventional techniques is marketed under the name KROTON G.TM., a product of the Shell Oil Company. ”
I think it was a typo and meant KRATON G, but the concept has been established anyway. If such is the case, the Unobtainium polymer:
https://en.m.wikipedia.org/wiki/Kraton_(polymer)