Oxetane,2,2,3,4-tetrafluoro-4-[1,1,3,4,4,6,7,7,9,10,10,12,12,12-tetradecafluoro-3,6,9-tris(trifluoromethyl)-2,5,8,11-tetraoxadodec-1-yl]-3-(trifluoromethyl)-