Methods for fabrication of silica aerogels with custom shapes using freeze drying

Abstract

A method of synthesizing aerogels and cross-linked aerogels are described that incorporate freeze-drying in lieu of supercritical solvent drying. Advantages over supercritical drying include a reduction in hazard risks posed by drying at supercritical conditions as well as the ability to up-scale the process to accommodate large pieces of material without introducing risk. In addition, inexpensive and more sophisticated mold technologies, which are not impervious to supercritical conditions, can be used to produce aerogel materials according to the freeze-drying method of the invention. This introduces a level of freedom never before available for the production of aerogel components.

1 - 64 . (canceled) 
     
     
         65 . A method of producing a hybrid aerogel, comprising:
 forming an alcogel from a gelation solution comprising a siloxane, polymerizable monomers, and a polymerization initiator;   activating the polymerization initiator in a selected pattern in the alcogel to form polymer in said selected pattern from the polymerizable monomers; and   drying the alcogel to produce a composite comprising a patterned polymer with aerogel cores in openings of the patterned polymer.   
     
     
         66 . The method of  claim 65  wherein the selected pattern is a honeycomb pattern. 
     
     
         67 . The method of  claim 66  wherein at least some of the aerogel cores are at least 50% visible light transmission. 
     
     
         68 . The method of  claim 66  wherein the drying is performed by freeze-drying. 
     
     
         69 . The method of  claim 66  wherein the aerogel cores are comprised of silica aerogel. 
     
     
         70 . The method of  claim 66  wherein said at least one acrylic monomer comprises a multifunctional acrylic monomer. 
     
     
         71 . The method of  claim 66  wherein said at least one acrylic monomer comprises two or more acrylic monomers. 
     
     
         72 . The method of  claim 66  wherein activating is performed by selective exposure to electromagnetic radiation. 
     
     
         73 . The method of  claim 72  wherein the electromagnetic radiation is or includes visible light. 
     
     
         74 . The method of  claim 72  wherein activating is performed by application of heat. 
     
     
         75 . The method of  claim 72  wherein the forming, activating and drying steps are performed in the same vessel. 
     
     
         76 . The method of  claim 72  wherein the polymerizable monomers are acrylates. 
     
     
         77 . The method of  claim 72  wherein the siloxane undergoes hydrolysis condensation. 
     
     
         78 . A hybrid aerogel, comprising:
 a patterned polymer with a plurality of openings;   aerogel in each of the plurality of openings in the patterned polymer, wherein the patterned polymer and aerogel are coextensive at the location of the patterned polymer with the patterned polymer conforming to the aerogel at the location of the patterned polymer.   
     
     
         79 . The hybrid aerogel of  claim 77  wherein the patterned polymer is in a honeycomb pattern. 
     
     
         80 . The hybrid aerogel of  claim 77  wherein at least some of the openings are at least 50% visible light transmission. 
     
     
         81 . The hybrid aerogel of  claim 77  wherein the polymer is a polyacrylate. 
     
     
         82 . The hybrid aerogel of  claim 77  wherein the aerogel is a silica aerogel.