Crystallinity control in covalent triazine frameworks: Synthetic approaches and mechanistic insights

Abstract

An important class of emerging porous organic materials is covalent triazine frameworks (CTFs), which have attracted much attention in wastewater treatment, energy conversion, and gas absorption due to their chemical and thermal properties and high nitrogen content. The synthesis of CTFs faces several challenges, including the reversibility of the reactions, which leads to structural defects and poor crystallinity. As a result, achieving high crystallinity is a major goal in the research and development of CTFs. This brief review focuses on the latest advances in the synthesis and control of crystallinity of these nitrogen-rich materials. The paper proceeds in order to review the principles governing crystal formation, the synthesis methods and factors affecting the reactions, and the final operations to prepare the product to enhance crystallinity. In addition, common crystallinity assessment techniques, including powder X-ray diffraction and advanced analysis, are reviewed. The effect of framework crystal structure on performance optimization is also discussed. Finally, challenges and future prospects in the development of synthesis techniques for the technological advancement of CTFs are presented.