Quantification was done by using 2-naphtol as the target molecule. 1 H-NMR results showed that an average of 0.71 mmol active TAD per gram of gel (Table ). It should be noted that some active TADs decomposed over time, without reacting with furan or 2-naphtol, which resulted in a smaller value than the actual value. Theoretically, a maximum of 1.65 mmol of TAD may be present if equimolar ethyl carbazate and triisocyanate are used at the beginning of the synthesis. The swelling ratio of the hydrogel was 87%. Scanning electron microscopy showed that the hydrogel has a porous structure like a sponge, with pore sizes between 12 and 30 µm (Fig. ).