Synthesis[edit]
Several methods are possible to prepare polyimides, among them:
The reaction between a dianhydride and a diamine (the most used method).
The reaction between a dianhydride and a diisocyanate.
Dianhydrides used as precursors to these materials include pyromellitic dianhydride, benzoquinonetetracarboxylic dianhydride and naphthalene tetracarboxylic dianhydride. Common diamine building blocks include 4,4'-diaminodiphenyl ether ("DAPE"), meta-phenylenediamine ("MDA"), and 3,3-diaminodiphenylmethane.[1] Hundreds of diamines and dianhydrides have been examined to tune the physical and especially the processing properties of these materials. These materials they tend to be insoluble and have high softening temperatures, arising from charge-transfer interactions between the planar subunits.[2]