Strong, compressible, bendable and stretchable silicone sponges by solvent-controlled hydrolysis and polycondensation of silanes.

Porous monolithic materials have wide potential applications in various fields. However, it is still very challenging to obtain flexible silica monolithic materials that could withstand diverse mechanical deformations. Here, we report a simple method for the preparation of strong, compressible, bendable and stretchable (SCBS) silicone sponges. The SCBS silicone sponges were fabricated by solvent-controlled hydrolytic polycondensation of silanes in the presence of co-solvents of water, followed by being dried at ambient pressure at 60 °C. The mechanical properties of the SCBS silicone sponges depend on their network structure, which is controllable by the co-solvents with different polarity, e.g., alcohols, alkanes and arenes. The co-solvents affect the network structure by influencing the hydrolysis and polycondensation of silanes in the sol-gel and phase separation processes. The SCBS silicone sponges are highly compressible (90%), bendable (20 mm) and stretchable (50%). The SCBS silicone sponges are also superhydrophobic/superoleophilic, and are promising materials for clean-up of oil contaminants from water surface. Moreover, the SCBS silicone sponges show high stability in a wide range of temperature (-196 to 300 °C). We believe that the SCBS silicone sponge will find applications in many fields, and the findings in this study will shed light on the design of novel silica monolithic materials.