First Macro-Mesocellular Silica SBA-15-Si(HIPE) Monoliths: Conditions for Obtaining Self-Standing Materials

Combining the emulsion and the cooperative templating mechanisms, self-standing macro-mesoporous SBA-15-Si(HIPE) monoliths (90-95% of porosity) have been synthesized for the first time. Materials have been prepared from the Pluronic (P123)/dodecane/water system in the presence of salt and TEOS as silica scaffold precursor. As increasing the ionic strength was shown to be ineffective toward obtaining self-standing monoliths, we induced a kosmotrope order maker effect within the starting silica gel making the use of (NH4)(2)SO4 salt to enhance silica polycondensation. Beyond its effect over the silica polycondensation, we show that the (NH4)(2)SO4 kosmotrope character has also a strong impact over the micelles organization at the mesoscale, with an input over the voids diameter and connections at the macroscopic length scale. The obtained SBA-15(x)Si(HIPE) self-standing foams exhibit thereby highly ordered mesopores, high specific surface area, and tunable open macroporosity while offering mechanical strength (Youngs modulus) of 0.15-1 MPa without collapsing at high strain.