Fluorinated main chain benzoxazine polyethers were prepared by Ullmann coupling of fluorinated benzoxazines in the presence of a nano-copperoxide catalyst. Various parameters such as the monomer structure, temperature, and the effect of catalyst on the polymerization were studied. The benzoxazine groups present in the polyether structure were shown to readily undergo thermally activated ring-opening polymerization in the absence of an added catalyst forming cross-linked networks. The thermal stability of the cured polymers was investigated and compared to that of classical polybenzoxazines. The lower surface energy of the fluorinated polymers made ultrathin films (similar to 20 nm thick) stable against dewetting at curing temperatures and resulted in thermally cured smooth coatings on solid substrates.