Facilitating mechanical strength in water-based polybenzoxazine aerogels via chemical cross-linking

Polybenzoxazine (PBz) aerogels have garnered significant attention as advanced thermal insulation materials, primarily attributed to their superior thermal stability and lightweight nature. However, their mechanical properties need further improvement for high-load scenarios. Furthermore, the reliance on toxic solvents, cumbersome preparation processes, and high costs has significantly impeded the advancement of PBz aerogels. Herein, we present a novel methodology for fabricating polybenzoxazine-based (PBz/KH562) hybrid aerogels with enhanced mechanical properties. By integrating 3-(2,3-epoxypropoxy) propylmethyldimethoxysilane (KH562) through a green process, the resulting aerogels demonstrate a low density (0.39 g·cm⁻³), low thermal conductivity (0.0556 W·m⁻¹·K⁻¹), and outstanding fire resistance. The optimized PBz/KH562 hybrid aerogels demonstrate a compressive strength of 8.45 MPa at 10% strain and 5.11 MPa at 5% strain, which increased of 451.87% and 477.57% compared to those of pristine PBz aerogels, respectively. Remarkably, the compression module is up to 101.15 MPa. This research establishes advanced green synthesis protocols, incorporates a novel dual-crosslinked architecture, and thereby facilitates the creation of high-performance insulating materials.