Out of all the pH values tested, the 5% CNC blend showed the highest swelling ratio, followed by the neat gelatin hydrogel, and then the 10% CNC gelatin blend. When the CNC content exceeded 10%, the swelling ratio gradually decreased. All CNC-gelatin hydrogels were expected to show increased swelling ratios due to the hydrophilic nature of the CNC, which would increase the water absorption of the hydrogel. However, our results showed that the 5% CNC-gelatin hydrogel achieved the highest swelling ratio. The swelling ratios then decreased at CNC concentrations >5%, which indicated a less swollen hydrogel. The lower swelling occurred because, as the percent of CNC increased, more space within the hydrogel network was filled up by CNCs, as shown in Fig. 2(B). This space fill-up resulted in the formation of a more rigid hydrogel structure, which is harder for water molecules to penetrate. Hence, the water absorption decreased, which led to a decrease in the swelling ratio.