I am do not know exactly but will you try CF3COOH. It is a good solvent for polyamides and at least contains F as your material. Be careful with rather toxic and aggresive solvent.
Manoj Kumar Dhal I can't say perfectly but as far as my knowledge of solubility thermodynamics goes, you can try PCBTF ( Parachlorobenzotrifluoride ). And I also agree with the idea of using Trifluoracetic acid by Valentin Talsi .