Mechanically Strong Polyimide Aerogels Cross-Linked With Dopamine-Functionalized Carbon Nanotubes For Oil Absorption

We report a novel procedure to fabricate vacuum dried high-mechanical-strength polyimide (PI) aerogels cross-linked with dopamine-functionalized carbon nanotubes (mCNTs). Poly(amid acid) chains are in situ grafted onto the surface of mCNTs via "grafting from" method, thus providing the composite aerogels with superior mechanical properties due to covalently chemical cross-link networks and linear reinforcement. The addition of only 1.0 wt% of mCNT endows the composite aerogel with the specific modulus of 715.5 J/g, which is much higher than that of chemical agent cross-linked aerogels. The obtained composite aerogels also show high thermal stability and enhanced flame retardant performance, with only a slight increase in weight loss and shrinkage after firing test. Furthermore, mCNTs can serve as secondary reaction platform, thus superhydrophobic and oleophilic composite aerogels were fabricated by grafting octadecylamine onto the aerogel surface. The water contact angle is as high as 151 degrees, and the maximum oil absorption capacity is 447%. Moreover, the composite aerogels exhibit stable hydrophobic and oleophilic properties after a long period of strong acid/base or high-temperature treatments, which is promising for practical oil-water separation applications under severe environments.