Investigating silica-surfactant interactions: when two techniques are better than one
01 Sep 2021



An International collaboration investigates the formation of silica surfactant particles.


​​Schematic of the surfactant-silica solution and the formation of a microporous thin film.​​


​By combining traditional Small Angle Neutron Scattering (SANS) and Spin-Echo Modulated Small Angle Neutron Scattering (SEMSANS) for the first time, an international collaboration was able to investigate the mechanism behind the initial growth of mesostructured silicasurfactant particles at the nano- and micro-metre scales simultaneously. The study, published in ACS Applied Materials & Interfaces, provides valuable insights on the formation of these particles, which are the precursors to thin films that grow at the solution interface. 

Two possible mechanisms for the self-assembly of these films from a silica-surfactant system have been suggested, but neither has previously been confirmed experimentally. This study used the unique combination of SANS and SEMSANS on Larmor to study the behaviour of the micelles and growing particles in solution to determine which mechanism occurs, under these conditions. 

The researchers were able to see the surfactant micelles elongate on addition of the silica species, before they aggregate to form droplets. After this droplet formation has occurred, the micelles inside the droplet order into large particles with an ordered mesostructure. The particles then migrate to the air/liquid interface, forming the thin film. The ability to manipulate the structure of mesoporous thin films, and the pore size within them, gives the films potential applications in a wide variety of fields including catalysis and drug-delivery.

Related publication: “Mesoporous Silica Formation Mechanisms Probed Using Combined Spin–Echo Modulated Small-Angle Neutron Scattering (SEMSANS) and Small-Angle Neutron Scattering (SANS).” ACS Appl. Mater. Interfaces, 12, 25, 28461–28473 (2020) DOI: 10.1021/acsami.0c03287

Contact: Jones, Evan (STFC,RAL,ISIS)