Reactions and stability of fluorinated poly(vinyl trimethylsilane) in electrochemical systems

Fluorinated poly(vinyl trimethylsilane) (FPVTMS) unlike virgin PVTMS is abl e to participate in electrochemical reactions and undergoes direct and indi rect electrochemical reductive degradation. Specifically, its perfluorinate d units are reduced irreversibly at a glass carbon electrode in a 0.05-M (C 4H9)(4)ClO4 solution in dimethylformamide with subsequent splitting of C-F bonds and formation of conjugated double bonds in macromolecules at the pol ymer surface. On the other hand, the incompletely fluorinated units at the FPVTMS surface interact with the previously electrochemically reduced backg round solution to be dehydrofluorinated. This is accompanied by the formati on of conjugated double bonds and dissolution of the dehydrofluorinated lay er also. The data obtained allowed distinguishing the incompletely fluorina ted units from the perfluorinated ones in the fluorinated layer of FPVTMS. Moreover, the quantity of the incompletely fluorinated units in FPVTMS can be determined. It was found that the strengthening of fluorination conditio ns led to an enhancement of the electrochemically induced FPVTMS transforma tions. (C) 2000 Elsevier Science Ltd. All rights reserved.