Surface modification of core-shell structured ZIF-67@Cobalt coordination compound to improve the fire safety of biomass aerogel insulation materials

Biomass materials are considered to be excellent candidates to replace petroleum-based materials, but inherent flammability limits their applications. In this work, biomass aerogel (BA) was prepared by freeze-drying method from sodium alginate (SA) and polyvinyl alcohol (PVA). To improve fire safety of BAs, a core-shell structured ZIF-67@Cobalt coordination compound was successfully synthesized, which was surface functionalized by 3,5diamino-1,2,4-triazole and 9,10-dihydro-9-oxo-10-phospho-diphenyl-10-oxide (DOPO), named as DOPO-NH2ZIF-67. The addition of DOPO-NH2-ZIF-67 (2 wt%) outstandingly improved fire safety of BA, in contrast to neat BA, peak heat release rate, peak smoke production rate, and total smoke production were reduced by 66.6%, 85.10%, and 72.76%, respectively. Furthermore, the incorporation of ZIF-67 and its derivatives has no adverse effect on the thermal insulation performance of BA composites and significantly improved their compressive strength from 0.27 MPa to 1.76 MPa. Preparation of core-shell structured ZIFs rich in active groups furnishes a conceivable way to synthesize an effective flame retardant, and a prospective method for the fabrication of aerogel insulation materials with green and economical additive-free technology is proposed.

Automated summary

In this study, biomass aerogel was prepared using a freeze-drying method and a novel core-shell flame retardant was successfully synthesized to significantly improve the fire safety performance of the aerogel. The addition of the new flame retardant not only enhanced the compressive strength of the aerogel without affecting its thermal insulation performance, but also reduced the peak heat release rate, peak smoke production rate, and total smoke production. This work provides a promising approach for the fabrication of aerogel insulation materials using green and economical additive-free technology.