Mesoporous silica formation mechanisms probed using combined Spin-Echo Modulated Small Angle Neutron Scattering (SEMSANS) and Small Angle Neutron Scattering (SANS).

The initial formation stages of surfactant-templated silica thin films which grow at the air-water interface were studied using combined Spin-Echo Modulated Small-Angle Neutron Scattering (SEMSANS) and Small Angle Neutron Scattering (SANS). The films are formed from either a cationic surfactant (CTAB) or non-ionic surfactant (C16EO8) in a dilute acidic solution, by addition of TMOS. Previous work has suggested a two stage formation mechanism with mesostructured particle formation in the bulk solution driving film formation at the solution surface. From the SEMSANS data, it is possible to pinpoint accurately the time associated with the formation of large particles in solution, that go on to form the film, and to show their emergence is concomitant with the appearance of Bragg peaks in the SANS pattern, associated with the 2D-hexagonal order. The combination of SANS and SEMSANS allows a complete depiction of the steps of the synthesis that occur in the subphase.