High-density Fibrous Polyimide Sponges with Superior Mechanical and Thermal Properties.

A relatively low compressive strength significantly limits the practical application of sponges made from electrospun fibers because of an ultralow density <10 mg/cm3. To solve this problem, fibrous polyimide sponges with high density (HDPISG) were prepared using a "self-gluing" concept. The HDPISG have a density of up to 280 mg/cm3 and porosity >80%, and showed good breathability. The compressive strength increased significantly as the sponge densities increased. The HDPISG with a density of 280 mg/cm3 has the highest compressive strength of 5190 and 35,900 kPa under 50 and 80% compression, respectively. The small HDPISG can even hold weights more than ten thousand times of the weight of the sponge. The HDPISG also possess excellent mechanical properties after thermal treatments and no loss of compressive strength can be seen after heating at 300 °C for 30 h. Further study indicates that the HDPISG can maintain their main shape after carbonization.