This result showed that glutaraldehyde crosslinked only gelatin chains with no effect on the CNCs. The peak at 1315 cm−1, 1104 cm−1, and 1057 cm−1, which belong to CNC, reappeared unchanged in the FTIR spectrum for the CNC-gelatin hydrogels. This reappearance proved that the CNC-gelatin hydrogel existed in the form of a semi-IPN, where both materials maintained their individual chemical structures. The proposed mechanism for the formation of a semi-IPN hydrogel is showed in Fig. 2(B).