The Effect of the Co‐Solvent on the Aerogel Formation Directly in Supercritical CO₂ Medium

Abstract

A series of flexible hydrophobic siloxane aerogels were obtained by the hydrothiolation reaction in supercritical CO2 medium in the presence of a co‐solvent. The effect of the co‐solvent nature on the aerogel morphology and physico‐mechanical properties were studied. n‐Pentane, a propane/n‐butane mixture, CH2Cl2, dimethyl ether (DME) and 1,1,2‐trichloro‐1,2,2‐trifluoro‐ethane were used as the co‐solvents. The morphology of aerogel particles was studied by SEM. In the case of n‐pentane, propane/n‐butane mixture, CH2Cl2, or DME as the co‐solvents, aerogels with a density of 0.18–0.21 g/cm3 and an average particle size of 0.15‐5.35 μm were obtained. Depending on the morphology, the mechanical properties of aerogels change in the range of 0.2–0.75 MPa (Young's modulus), 38–68 % (compressibility) and 0.11–0.42 MPa (stress rupture). In the case of 1,1,2‐trichloro‐1,2,2‐trifluoro‐ethane as the co‐solvent, the aerogel with an inhomogeneous structure was obtained. All the aerogels studied have a large water contact angle in the range of 142°‐151°.

The Use of the Thiol-Ene Addition Click Reaction in the Chemistry of Organosilicon Compounds: An Alternative or a Supplement to the Classical Hydrosilylation?

“…The main advantage of this method is that the drying stage can be eliminated from the overall process, which saves time and resources. Functional siloxanes [ 164 , 165 ] or phosphazenes [ 166 ] are used as the starting reagents.…”