科研之友
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摘要
Polymerization of trifunctional polyaromatic carboxylic acids and isocyanates in dilute DMF solutions using the rather underutilized reaction of the carboxylic acid group (-COOH) with isocyanates (-N=C=O) towards amides (-NH(C=O)-) induces early phase separation of surface-active aramid nanoparticles that form a solvent-filled 3D network stabilized against collapse by the chemical energy of the interparticle covalent bridges (crosslinks). Those wet-gels can be dried with liquid CO2 taken out at the end as a supercritical fluid into lightweight (bulk density similar to 0.3 g cm(-3)) highly porous (77% v/v) multifunctional materials classified as aerogels with high specific energy absorption (37 J g(-1)), open-air speed of sound (338 m s(-1)) and Styrofoam-like thermal conductivity (0.028 W m(-1) K-1).
- 出版日期2011
