NMR study of the polysiloxaneimides doped with LiCF3SO3

Complexes were prepared by cosolution of the lithium trifluoromethanesulfonate (LiCF3SO3) and the polysiloxaneimides (PSI). PSI copolymers were synthesized by polycondensation reaction of 3,3',4,4'-benzophenone tetracarboxylic dianhydride with oxydianiline and, alpha,omega-aminopropyl siloxane of varying molecular weights. The Si-29 and C-13-CPMAS NMR spectra and the spin-spin relaxation of complexes have been studied to probe the role of the salt. Si-29 NMR spectra of PSI-Li complexes showed two kinds of silicon, which may be assigned to siloxane sequences and siloxane units directly attached to PI. Lithium salt reduces the mobility of the siloxane sequences in PSI-Li complexes. This effect is explained by the interaction between the Li+ and the oxygen atoms in the polymer backbone.