“…The FT-IR spectra of the pristine SiO 2 , AEO3-SiO 2 , AEO7-SiO 2 , and AEO9-SiO 2 species exhibited two absorption peaks at ∼3440 and 1633 cm −1 , which were assigned to the bending and stretching vibrational modes of the −O−H bonds, respectively. In addition, two strong absorption peaks were present at 1107 and 808 cm −1 , which originated from the antisymmetric and symmetric stretching vibrations of Si−O−Si, 53 respectively (Figure 1a). Notably, the areas of the ∼3440 cm −1 peaks of AEO7-SiO 2 and AEO9-SiO 2 are smaller than that of the pristine SiO 2 , indicating that the surface hydroxyl groups of the silica NPs may react with AEOn.…”