The GMO55HEA10 film showed an Im3m phase with a lattice parameter of 12.5 nm after 1 min, decreasing to 11.8 nm at 30 min of polymerization (see Figure ). The Bonnet ratio for GMO60HEA5 calculated from the lattice parameters of the Pn3m structure at t = 1 min and for the coexisting Im3m structure at t = 15 min corresponded to 1.36, which is still in the range of previously reported values for Pn3m/Im3m conversion in non-equilibrium condition. The time-resolved GISAXS studies also show the tendency of the Pn3m-to-Im3m transition to increase in a concentration-dependent manner. For GMO60HEA5, the first reflection peak of the Im3m structure at q ~ 0.7 nm-1 appears after ~5 min, whereas for GMO55HEA10, its presence is already observed at ~1 min of reaction, see Figure . The faster phase transition to the Im3m phase may result from the higher HEA content inside the GMO55HEA10 film.