Crystalline Covalent Organic Frameworks Meet Low Temperature Hybrid Glasses: Synthetic Strategies and Interfacial Interactions

Hybrid glasses have attracted increasing attention due to their versatility and low melting temperatures, which make them promising matrices for composite formation. Covalent organic frameworks (COFs), in turn, offer high crystallinity, permanent porosity, and tunable chemistry, yet their poor processability limits practical applications. Herein, we combine both to develop COF@Glass composites that overcome this limitation. Two preparation strategies were studied in parallel using two different COFs, and the in situ melting of the glass in the presence of the COFs outperformed the alternative strategy and physical mixing, preserving the integrity of both phases while generating a distinct COF-Glass interface. This interface was investigated by X-ray pair distribution function analysis combined with principal component analysis, which provided insight into the chemical nature of the interactions between the components, and further examined by diffuse reflectance spectroscopy. This work establishes a route to COF@Glass composites, expanding the processing possibilities of COFs.