Table 2. Chemical Structures of Crosslinkers Used

Difunctional crosslinker	Trifunctional crosslinker
Tetra(ethylene glycol) diacrylate (TTEGDA	Trimethylolpropane triacrylate (TMPTA)

Reaction conditions: degree of neutralization=40 mol%, crosslinker content=1.5 wt%, initiator content (APS)=0.75 mol/L, and medium volume=50 mL.