Silica Nanoparticles Three Dimensional Assembly: An Integrative Chemistry Approach Toward Designing Opal-Like Silica Foams

Abstract

AbstractNovel meso-/macroporous SiO2 monoliths have been reached by applying a nanotectonic pathway within a confined geometry, i.e. a non-static air-liquid foam pattering process. Final scaffolds are a very close transcription of the tailored periodic air-liquid foam template while highly ordered close-packed silica colloids are texturing the as-synthesized foam walls. The interconnected nanoparticles and associated void space between adjacent particles allow generating intrinsic mesopores, thereby defining hierarchically organized porous scaffolds. The good control over both the air-liquid foam's water volume fraction and the bubble size allow a rational tuning of the macropore shape (diameter, Plateau border's width). At the nano-scale, heterogeneous textural character is associated with abrupt variation in the film's topology certainly governed by the complex liquid flow present within the foam film. This flow induces a surfactant concentration gradient that causes a sort of marginal regeneration on the side of the film. According to these observations, the heterogeneous character of the film surface revealed by AFM can be interpreted like a direct expression of the liquid flow within the air-liquid foam's film.