Sodium Naphthalenide Diglyme Solution for Etching PTFE, Characterizations and Molecular Modelization

Wet etching of polytetrafluoroethylene by sodium naphthalenide dissolved in diglyme solution was investigated experimentally and theoretically. First, the irreversible modification of the polymer surface was analyzed by Raman and XPS spectroscopies, water wetting angle measurements and AFM observations. The drastic changes brought to the surface of PTFE could be clearly demonstrated by these analytical methods. Then, first principle calculations coupled to molecular dynamics (FPMD) were performed to simulate the first steps of the reaction involved in the process of surface modification. It has been shown that fluorine directly attacks vicinal sodium with formation of a pair of sodium fluoride ions without grafting of the naphthalene moiety onto the modified surface. While the formation of the alkene and alkyne bond can be modelized, no spectroscopic signature is observed after rinsing etched PTFE.