Multifunctional Polyurea Aerogels from Isocyanates and Water. a Structure-property Case Study

摘要: It is well-known that isocyanates and water yield polyureas; however, reaction not generally associated with the synthesis of latter, being used instead for environmental curing films baring free NCO groups or foaming polyurethanes. Here we report careful control relative isocyanate/water/catalyst (Et3N) ratio in acetone, acetonitrile, DMSO prevents precipitation, yielding polyurea (PUA) gels convertible to highly porous (up 98.6% v/v) aerogels over a very wide density range (0.016−0.55 g cm−3). The method has been implemented successfully several aliphatic aromatic di triisocyanates. PUA have studied at molecular level (13C NMR, IR, XRD), elementary nanoparticle (SANS/USANS), microscopic (SEM). Their structure probed N2-sorption porosimetry. Despite nanomorphology varies from fibrous low end particulate high end, all samples consis...