THIN AEROGEL FILMS FOR OPTICAL, THERMAL, ACOUSTIC AND ELECTRONIC APPLICATIONS

Aerogels are a special class of continuously porous solid materials wh ich are characterized by nanometer size particles and pores. Typically , aerogels are made using sol-gel chemistry to form a solvent filled, high porosity gel that is dried by removing the solvent without collap sing the tenuous solid phase. As bulk materials, aerogels are known to have many exceptional, and even some unique physical properties. Aero gels provide the highest thermal insulation and lowest dielectric cons tant of any other material known. However, some important applications require the aerogels in the form of thin films or sheets. For example , electronic applications require micrometer thin aerogel films bonded to a substrate, and others require thicker films, either on a substra te or as free standing sheets. Special methods are required to make ae rogel thin films or sheets. In this paper, the special conditions need ed to fabricate thin aerogel films are discussed and methods to make f ilms and thin sheets are described. Also, some specific applications a re given for which aerogel films are being developed.