Polyimide aerogels using melamine as an economical yet effective crosslinker

Polyimide (PI) aerogels with crosslinked structure are promising for diverse applications owing to their nano-porous nature and superior properties in many aspects. However, the crosslinkers used for preparing crosslinked PI aerogels are always laboriously available and expensive. The economical melamine therefore was chosen as a substitute in this study. It was proved that the use of melamine was indeed a viable strategy for effectively crosslinking PI chains. The resultant melamine-crosslinked PI (MPI) aerogels were tested to have relatively low shrinkage (as low as 9.96 vol%), ultralight bulk densities (0.084–0.116 g cm−3) and low thermal conductivity (< 40.0 mW m−1 K−1), together with considerable thermal stability (onset temperature to decompose up to 503 ℃) and acceptable compressive strength (Young’s modulus of 1.12–10.04 MPa). Meanwhile, the morphology and properties of MPI aerogels can also be tailored by regulating the proportion of hybrid diamines as well as the polymer concentration of pristine solution. Given all of these, MPI aerogels using melamine as an economical yet effective crosslinker will have a broad prospect in many fields including thermal insulation.