Melt polymerization synthesis of a class of robust self-shaped olefin-linked COF foams as high-efficiency separators

The practical applications of crystalline porous materials toward industrial separations require shaping them into robust monoliths (e.g., foams). The current methods are often complicated, environmentally unfriendly, and unscalable, significantly hampering their practical application. Herein, we report a scalable, facile “one-step thermomolding” method to fabricate a class of hierarchically olefin-linked covalent organic framework (COF) foams via melt polymerization. The obtained pure COF foams possess higher crystallinity and porosity than literature, good moldability, and processability, greatly benefiting their practical applications (e.g., efficient oil-water separation with 99% removal efficiency and >100 cycle reusability). Moreover, a COF exhibiting the smallest (0.58 nm) eclipsed stacking pore among all 2-dimensional COFs with neutral skeletons is first fabricated via this protocol, demonstrating good C2H2 purification performance and recyclability, surpassing the current benchmark materials. We believe that this facile fabrication strategy can promote access to a broad diversity of new COF foams and enlighten further avenues for green routes to large-scale synthesis and usage of COFs.