Additional surface-sensitive in-situ infrared experiments (DRIFTS; see Figure ) were performed on HPAN_PEI1 at 120 °C (to get rid of the broad O-H stretching band from 2800 to 3600 cm -1 due to surface hydration). It revealed characteristic peaks of amine (3420 and 2850 cm -1 ) as well as alkane (2925 and 1450 cm -1 ) and nitrile (2240 cm -1 ) moieties, which confirmed the results obtained from ATR-FTIR.