Characteristic FTIR peaks present in the synthesized hydrogel samples.

Functional Groups	Wave number (cm−1)
Carrageenan
d-Galactose-4-sulphate	850–840
3,6-Anhydro-d-galactose	940–910
Glycosidic linkage	1100–1020
Sulphate ester	1270–1210
O–H stretching	3400–3000
Water
H–O–H bending	1670–1650
PVA
O–H stretching	3750–3100
APTES
Si–O–Si	1100–1020
–CH stretching	2921
Si–OH	3725