Engineering Three Dimensional Nanotextured Opal-Like Silica Foams
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0901-Ra22-20-Rb22-20.1
Engineering Three Dimensional Nanotextured Opal-Like Silica Foams F. Carn*, P. Massé, S. Ravaine and R. Backov Centre de Recherche Paul Pascal CNRS UPR 8641, 115 Ave Albert Schweitzer, 33600 Pessac, France. [email protected]
ABSTRACT Novel meso-/macroporous SiO2 monoliths have been reached by applying a nanotectonic pathway within a confined geometry, i.e. a non-static air-liquid foam patterning process. Final scaffolds are a very close transcription of the tailored periodic air-liquid foam template while coalesced silica particles 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 allows a rational tuning of the macropore shape (diameter, Plateau border’s width). In contrast with previous study, closedcell structures can be reached, while the opal like scaffold structure is maintained with thermal treatment, avoiding thus strong shrinkage associated to the sintering effect. INTRODUCTION The synthesis of micro- and / or meso-porous inorganic materials is a very competitive and quite mature research area regarding the wide range of strategies proposed in the literature [1,2]. Beyond those meso- and/or nanoscopic concerns, the properties of final porous materials are also strongly related on the way of the solid is textured at the macroscopic length scale [3]. In this specific issue of high scale organization, shaping macroscopic monolith in the form of highly open-cell macroporous network with well defined topology, morphology and cell dimension appears as an important task to reach that strongly influences the suitability toward potential applications as thermal and/or acoustic insulation [3], tissue engineering [4] or heterogeneous catalysis [5]. Considering this general context, materials with higher order architecture can be prepared by different route involving self-assembly [6], shape directed assembly [7], even layer by layer assembly [8] when considering bidimensional systems. A promising approach to engineer hierarchically organized materials with macropore diameter ranging from 5 µm up to 600 µm involves the use of complex fluid such like biliquid [9-11] or air-liquid foam [12-16]. However, the rational control of the macropore architecture (i.e. dimension and morphology) and connectivity (i.e. topologic aspect), associated with an enhanced structural stability toward moisture, thermal treatment and compression remains an experimental challenge. In the present study we propose a new synthesizing route by achieving the very close transcription of a tailored air-liquid foam periodic structure using confined colloids as nano-building blocks. This strategy allows reaching stable opal-like silica foam architectures.
0901-Ra22-20-Rb22-20.2
EXPERIMENTAL DETAILS Syntheses Tetraetoxysilane (TEOS, Fluka Chemica), amm
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