[stina224]

I am trying to take contact angle measurements of ionic liquids.  I am currently using teflon but am needing to increase the surface smoothness.  Is there a way that I can do this?  Or, is there another surface that is ultrahydrophobic?

[Enthalpy]

Smoother Ptfe: grinding a plastic surface is generally disappointing. If you can, choose or produce an other part of Ptfe, better machined (easy with Ptfe) or injected. Ptfe can be very smooth.

Very hydrophobic:
Silicone
Polyethylene
Polypropylene
Hydrophobic coating sprays

[hugh111111]

You can achieve a quite impressive super-hydrophobic (contact angle > 150 deg) surface by dispersing hydrophobic fumed silica as a filler into a film forming polymer. Aerosil fumed silica from Evonik-Degussa produces an excellent super-hydrophobic effect