Ultralight, super thermal insulation, and fire-resistant cellular cement fabricated with Janus nanoparticle stabilized ultra-stable aqueous foam

Bubble-templated advanced cellular materials with ultralight and superior thermal insulation properties have shown great potential in energy-saving related applications. However, insufficient bubble stability severely limits the generation of such highly porous structures . Herein, we present an efficient method to produce ultra-stable aqueous foams by combing the amphiphilic Janus nanoparticle (Janus-SiO 2 ) with the surface-active polymer (hydroxypropyl methylcellulose). The life of aqueous foams is dramatically increased from 4 h to over 5 days with 5 wt% Janus-SiO 2 concentration. The dense adsorbed layer formed by the efficient adsorption of Janus-SiO 2 on the bubble film is the main factor for the outstanding foam stability. Owing to the greatly enhanced foam stability, we successfully produce ultralight cellular cement with hierarchical cellular structures and a density as low as 80 kg/m 3 . The ultralight cellular cement exhibits superior mechanical strength , robust fire resistance and excellent thermal insulation with a thermal conductivity as low as 0.038 W·m −1 ·K −1 . This work provides a practical approach for fabricating various advanced porous materials that employ bubbles as templates.