Reliable measurement of chemical structure changes in polyimide ion tracks using an improved ATR-FTIR method

Ion-track membranes (ITMs) with special chemical structures have great potential application prospects in the field of membrane separation. Accurate detection of chemical modifications induced by irradiation is crucial for a deeper understanding of the formation mechanism of ion tracks and their internal transport properties of materials. In this study, an improved attenuated total reflection (ATR) method was proposed to semi-quantitative analyze the chemical structure changes in polyimide ion-track membranes (PI-ITMs). Chemical degradation in PI-ITMs was systematically investigated under different irradiation conditions with fluence and electronic energy loss (Se). The damage radii of different functional groups were calculated and showed a linear increasing trend with increasing Se. The damage radius for different functional groups with Se shows a radical distribution and depends on the strength of their chemical bonds. The weak bands assigned to the carbon–carbon triple bonds, carboxyhydroxyl, methyl and methylene groups were confirmed and analyzed semi-quantitatively after avoiding interference fringes. The alterations and possible mechanisms of these groups were also discussed in this work.