“…To date, dissolution of PEEK has been reported in concentrated acids such as sulfuric acid, chlorosulfonic acid, hydrofluoric acid, methanesulfonic acid, trichloromethanesulfonic acid, trifluoromethanesulfonic acid, polyphosphoric acid, dichloroacetic acid, and a mixture of trichloroacetic acid with 1,1,2,2-tetrachloroethane . Limited solubility requiring elevated temperatures has also been reported in high boiling point solvents including: benzophenone, , 4-chlorophenol, diphenyl sulfone, α-chloronapthalene, sulfolane, and a mixture of phenol and 1,2,4-trichlorobenzene …”