The amount of condensed counterions is calculated by analyzing the trajectories of the individual Na + counterions around each constituting chain of the hydrogel. In order to calculate the population of microscopically condensed counterions, we define the condensation with respect to the localization of a counterion to an oppositely charged backbone (i.e. oxygen) atom . If the distance between the backbone charge and the counterion d ≤ 0.25 nm, then the counterion is considered to be condensed (see Figure ). The threshold distance d corresponds to a steric contact between the oxygen atom and the counterion. We also calculate the distribution of the counterions around the individual polymer chains in the cylindrical coordinates . The main axis of the cylindrical coordinate system for each chain is determined by the positions of the terminal crosslinker beads. The number of counterions n(ρ) within any radius, ρ, is calculated, and the distribution is integrated to obtain the cumulative number of condensed counterions via