Simple and fast method for producing flexible superhydrophobic aerogels by direct formation of thiol-ene networks in scCO^sub 2

A new fast (about 1.5 h) and simple method for producing light-weight polymeric aerogels by radical thiol-ene click reaction direct in the scCO2 media is described. A series of flexible, monolithic and superhydrophobic polysiloxane aerogels based on vinyl- and thiol-containing precursors have been synthesized by this method. The influence of precursor structure on the aerogel properties has been investigated. Bulk densities for synthesized aerogels were between 0.097 and 0.44 g cm-3 and skeletal densities of these aerogels were in the range of 1.171-1.215 g cm-3. All investigated polysiloxane aerogels exhibit excellent thermal stability. The weight loss is observed to begin at about 300 °C in air and about 370 °C in argon for all samples. The compressive modulus of the aerogels ranged from 0.025 to 2 MPa. All samples have porosity in the range of 63-93% and a very low specific surface area. The developed method for producing aerogels by Direct Sol-Gel polymerization in SuperCritical Fluid (DSGSCF) seems to be interesting and perspective in the row of fast and cost-effective methods.