About PTFE|Polytetrafluoroethylene (Teflon). The lowest friction of any solid material and chemically inert to virtually everything. Soft (Shore D 50-55), which means it deforms under load and requires creative workholding. Machines easily but the material is slippery and doesn't clamp well, so use vacuum fixtures or wrap it. Used for seals, gaskets, bearings, insulators, and chemical-resistant linings. Compare to
UHMW (much tougher, slightly higher friction) and
PEEK (much stronger, similar chemical resistance, much more expensive).