Azide Thermolysis Frameworks: Self‐inflating, Porous, and Lightweight Materials

Porous organic materials have received increasing attention due to their potential applications, such as gas storage, gas separation, and catalysis. In this work, we present a series of aromatic, polyazide-containing building blocks that enable the formation of a new class of amorphous porous organic materials. The azide precursors are obtained in moderate to good yields following an easy synthesis procedure. By thermal decomposition, self-inflating porous structures named Azide Thermolysis Frameworks (ATFs) can be obtained. Modified thermogravimetric analysis is used to determine the onset temperature at which the azides decompose and the frameworks are formed. The frameworks are further investigated via infrared (IR) spectroscopy, elemental analysis, scanning electron microscopy (SEM), and gas adsorption measurements. Specific surface areas and pore sizes are determined by nitrogen adsorption measurements at 77 K using the Brunauer–Emmett–Teller method (BET) to give surface areas of up to 677 m$^2$/g for the ATF resulting from the thermolysis of TPB-Azide at 450 °C, which can compete with early Covalent Organic Frameworks (COFs). The specific surface area can be tuned by varying the thermolysis temperature.