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

Abstract

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-SiO2) 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-SiO2 concentration. The dense adsorbed layer formed by the efficient adsorption of Janus-SiO2 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/m3. 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.