Silver nanoparticles cross-linked polyimide aerogels with improved high temperature microstructure stabilities and high mechanical performances

Nanoparticles can be considered as effective cross-linkers for PI aerogels. In order to investigate the effect of different nanoparticle-cross-linkers on the performances of aerogels, two types of silver nanoparticles, AgNPs (Ag nanoparticles) and AgNShs (Ag nanosheets) were modified via PATP (p-aminothiophenol) as cross-linkers and then added into PAA (polyamic acid) solution derived from BPDA (3, 3′, 4, 4′-biphenyltetracarboxylic dianhydride) and ODA (4, 4′-diaminodiphenyl ether) to form wet gel. The wet gel was processed with supercritical CO₂ drying to fabricate cross-linked polyimide aerogels. Raman, XPS and TG-IR were carried out to prove successful modification of silver nanoparticles. The as-prepared aerogels had densities around 0.2 g cm⁻³. Nitrogen adsorption desorption tests and mechanical tests were conducted to characterize the performance of aerogels at room temperature and high temperature (above 150 °C). The results showed that comparing to pure PI aerogels, aerogels cross-linked with silver nanoparticles had higher compressive strength and Young's modulus, which comes to 3.4 MPa and 52.7 MPa, respectively. Besides, silver nanoparticles cross-linked aerogels also had better high temperature stability in both size and microstructure comparing to pure PI aerogels. With remarkable mechanical properties and high temperature microstructure stabilities, these aerogels show potential in many areas of application.