A Dual-Modified Chitosan-Derived Silica Composite Aerogel with Simultaneous Improvement of Mechanical, Flame Retardancy, and Thermal Insulation Properties

Energy-efficient buildings require materials with low thermal conductivity, and high fire resistance and mechanical properties. Traditional chitosan aerogel is limited by its poor fire resistance and silica aerogel is either brittle or displays a high thermal conductivity. Herein, we report a dual-modified aerogel with high mechanical properties, low thermal conductivity, and excellent fire resistance. Briefly, the chitosan-derived silica aerogel (CA) was first fabricated, followed by loading varying contents of phytate-piperazine (PPA) intumescent flame-retardant. This well-designed aerogel (CA/PPA) combines with the high mechanical strength of chitosan aerogel, the excellent fire resistance function of silica aerogel, and the intumescent flame-retardant performance of PPA. The as-created CA/PPA-2.0 exhibited enhanced mechanical properties, as evidenced by the fact that its compressive strength rose from 1.3 ± 0.10 to 2.9 ± 0.23 MPa at 90.0% strain compared to that of neat chitosan aerogel. Additionally, compared to CA, the CA/PPA aerogel with 2.0 wt% PPA exhibits significant fire safety performance. For instance, the peak heat release rate, total heat release, maximum average rate of heat emission, and thermal conductivity were reduced by 62.1%, 55.6%, 48.4%, and 12.5%, respectively. In addition, the CA/PPA-2.0 composite aerogel also exhibits a fire-alarm performance under flame attack. This work introduces a feasible strategy to produce high-performance aerogels with promising applications in construction, aerospace, and thermal insulation.