Aerogels are nanostructured materials with the lowest density compared to other materials and according to their composition, they have special applications in different fields. Aerogels are synthesized in a first step by low-temperature traditional sol-gel chemistry. While in the final step most wet gels are dried by evaporation to produce xerogels, aerogels are dried by other techniques, essentially supercritical drying. These materials with bulk density of 0.003-0.35 g/cm3 are known as the lightest solid materials. Also, aerogels have the lowest thermal conductivity in comparison with other solid materials. Some polymeric nanoaerogels are: resorcinol-formaldehyde, polyurethane, cellulosic, cross-linked polymer and biopolymer-containing aerogels. Depending on the synthesis process, structure, physical and mechanical properties, these nanomaterials can be used in various industries including electronics, optics, mechanics, aerospace, medical, pharmaceutical and etc. In this paper, the aerogel production procedure is briefly reviewed and then types of polymeric aerogels, their synthesis, properties and special applications are summarized.
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