“…In the N 1s scans, peaks assignable to N + –C, N–C, and N=C were observed at 400.9, 399.5, and 398.2 eV, respectively (Figure 2). 34,35 In the case of the mPBI powder, relative areas of N–C and N=C peaks largely increased, and that of the N + –C peak decreased compared with that of the other samples (Figure 2a, see also the Supporting Information, Table S1a), which indicated the loss of the cation group through the S N 2 reaction, as explained in Scheme S1. It is noted that only some of the mPBI powder dissolved and the XPS measurements were obtained from the residual powder.…”