Greatly strengthened silica aerogels via co-gelation of binary sols with different concentrations: A method to control the microstructure of the colloids

• A new approach to control the microstructure of the colloids.
• Co-gelation of binary sols with different concentrations.
• Final aerogels with excellent performance in multitudinous physical properties.
• Improved the fragile skeleton chains and loose internal structure of silica aerogel.
• Method can be used more extensively in developing porous materials.

In this paper, we introduced an improved way to control the microstructure of the colloids via co-gelation of binary sols with different concentrations method (CBS). The approach was developed to maintain typical silica particles derived two target density single-sols, and these typical silica particles with distinct diameters (large: 10–12 nm; small: 3–5 nm) were interconnected into a special skeletal framework and internal structure for silica aerogels. BET observation, SEM analysis, and TEM study indicate differences in pore size distributions and surface morphology for aerogels prepared by conventional (single-sol) and CBS (mixed-sol) chemistry approaches. Hence, the CBS method can enable us to obtain mixed aerogels with excellent performance in various physical properties, DMA and UV–vis results suggest that better mechanical property and higher optical transmittance are dominated by the special nanostructure rather than by some unique properties of silica aerogels. Effective hydrothermal treatment technique was used to shorten gelling time significantly and promote silica particles to grow freely during the sol–gel reaction process. These results have important implications for designing novel structure of porous materials and for understanding observations of high performance for silica aerogels.

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