Fluctuations and growth of a cubic network observed in a nonionic surfactant system

We have investigated stability of a cubic lattice having a periodic-minimal surface in a nonionic surfactant system using a time resolved small-angle neutron scattering technique. The cubic lattice transformed from a lamellar phase showed polycrystalline scattering patterns and a strong fluctuation of the diffraction intensity as a function of time. The intensity distribution analysis indicates that the domain coarsening proceeds until 2000 min and then the coarsening is suppressed. At a critical temperature, such fluctuating peaks suddenly grow to a monocrystalline pattern showing no intensity fluctuations. On the contrary, in the case of the cubic lattice transformed from a hexagonal phase, the polycrystalline diffraction peaks also showed fluctuating behavior, but in this case, the domain coarsening is suppressed and the scattering intensity fluctuates around an equilibrium value. We consider that the fluctuations arise from the polycrystalline cubic network trapped in a metastable state.