Doping of ion irradiated poly(aryl ether ether ketone) from water solutionof LiCl

Poly(aryl ether ether ketone) (PEEK) films were irradiated with 2 MeV O+ io ns to fluences up to 6x10(14)cm(-2) and then doped from a 5 molar water sol ution of LiCl. The depth distribution of the incorporated LiCl was investig ated using neutron depth profiling, and electron paramagnetic resonance was used for the determination of the concentration of free radicals. The stru ctural changes of the modified PEEK were examined by IR spectroscopy. Measu rement of the sheet resistivity and its temperature dependence gave informa tion on the electrical properties of the modified PEEK. The results show th at the ion irradiation enhances the penetration and incorporation of the Li Cl dopant in the radiation-damaged PEEK surface layer. The Li atoms are che mically bound to free radicals created by radiation-induced degradation of PEEK macromolecules. The ion implantation leads to an increase in the PEEK conductance, which is further elevated by the LiCl doping. The conductance enhancement is partly a variable-range hopping mechanism and also electron hopping due to bound Li+ ions. (C) 1998 Elsevier Science Limited. All right s reserved.