tgel is the time needed to reach the crossover point of storage and loss modulus, G' = G", which is usually called the gel point. At tgel, the polymer solution transitions from a liquid-like (viscous) behaviour to a solid-like (elastic) state corresponding to a three-dimensional network. G'20min reflects the stiffness reached by the hydrogels after crosslinking and 20 min light exposure, which in our case corresponds to the plateau value of the shear modulus after full exposure.