“…The absorption band of the gel within 3140–3370 cm −1 is the O–H vibrational stretching of intramolecular and intermolecular hydrogen bonding within PVA, and this broad peak is slightly shifted within this range, suggesting that SiO 2 and PEG have little effect on the structure of PVA. 23 The absorption band at 2920 cm −1 is the asymmetric stretching mode of –CH 2 – and the absorption band at 1070 cm −1 is the C–O vibrational mode of the amorphous region in the PVA base. 24 It is noteworthy that the addition of SiO 2 and PEG caused the –OH vibrational modes significantly move to lower wave numbers, and the intensity of the C–O vibrational bands was also significantly weakened, suggesting that the introduction of SiO 2 and PEG reduced the crystallinity of PVA, which is consistent with the XRD results.…”