3.2.1. Initiator (KPS) Concentration

The swelling percentage of GT-cl-poly(DMA) hydrogel was affected by the concentration of KPS and results are shown in Figure 1a. The maximum swelling of 565.5% was observed at <sup>10</sup> <sup>×</sup> <sup>10</sup>−<sup>1</sup> mol L−<sup>1</sup> of KPS. Below this concentration (<10 <sup>×</sup> 10−<sup>1</sup> mol L−1), the swelling percentage was lower due to inadequate initiator, which was unable to produce appropriate active sites on GT-cl-poly(DMA).

**Figure 1.** Effect of (**a**) initiator (KPS) concentration, (**b**) reaction time (s), (**c**) amount of solvent (mL), (**d**) microwave power (%), (**e**) monomer (DMA) concentration, (**f**) cross-linker (NMBA) concentration and (**g**) amount of reduced graphene oxide (RGO) on gum tragacanth-cl-*N,N*-dimethylacrylamide hydrogel swelling.
