Mechanically Strong Nanoporous Polyimides (Aerogels) from Anhydrides and Isocyanates: A Structure-Property Study

摘要

Aerogels are lightweight nanoporous solids that nearly eliminate convective heat transfer and thus combine low density with low thermal conductivity, both desirable for thermal insulation [1]. A major drawback, however, has been their poor mechanical properties. In that regard, it has been reported as early as in the 1930s that organic aerogels are more robust materials than their oxide counterparts [2], a fact confirmed by recent more systematic studies [3]. It is hence reasonable to pursue further development among engineering plastics, as for example polyimides (PI), which demonstrate excellent mechanical properties as well as high temperature stability [4], and are used widely as matrix resins for fiber-reinforced composites in aircraft engine applications. Thus, PI aerogels would be ideal materials for high temperature thermal insulation as reflected by the increased activity in that area [5].