The average number of NPs in the distance corresponding to each peak can be computed by the integration of the g(r) peak (Equation , where r 1 and r 2 are the positions of the minima before and after the maximum of interest), and those values where included close to corresponding peaks of g(r) in Figure for each time interval. Comparing the hydrophobic and the hydrophilic NPs in C4, one can notice the aggregation is faster for the hydrophilic NP which displays the smallest barrier for the dimer association across the four systems studied (Figure ).