The equilibrium water content (EWC) of the PEtOx/polyperoxide based hydrogels was determined after crosslinking with different concentration of crosslinker (P[PM-co-MA]), crosslinking time and temperature (Figure ). The investigation of swelling was performed in deionized water at room temperature. It appears that the EWC is affected by all three crosslinking parameters with the crosslinking time having only minor influence on EWC. In contrast, the crosslinker concentration and the crosslinking temperature appear to have a more pronounced effect. For P[PM-co-MA] crosslinker concentrations of 10 and 15 wt. % and at temperatures ≤ 160 °C, the influence on the EWC was not systematic (Figure ). Interestingly, at 180 °C, there seems to be a small, but systematic decrease in EWC with increasing incubation time. At 20 wt. % crosslinker, consistently the lowest EWC values were obtained (Figure ). The most obvious correlation could be observed between the crosslinking temperature and EWC; a higher temperature leads to a lower EWC. For example, at 10 and 15 wt.% and 120-160 °C, EWC was found at 96.20 ±0.31 %, which decreases to 93.64 ± 0.37 % at 180 °C and 91.89 ± 0.09*10 3 % at 200 °C, respectively. At 20 wt. %, the overall EWC values are smaller but the trend remains clear. While at 120 °C, the EWC ranges from 94.36 ± 0.21 %, it is reduced to 85.21 ± 0.40 % at 200 °C.