Recent progress in single-crystal structures of organic polymers

Growing single crystals of organic polymers is very important but extremely challenging. Currently, such a field has received substantial attention and inspiring progress has been witnessed. Thus, it is the right time to provide a review on suitable polymer single crystals, whose structures have been clearly confirmed by single crystal X-ray diffraction or electron diffraction analysis. In this mini-review, a summary has been given based on the following branches: (a) linear polymer crystals; (b) polymer single crystals obtained through topochemical polymerization in a single-crystal-to-single-crystal (SCSC) transformation; (c) single crystal growth of covalent organic frameworks (COFs); and (d) growth of polymer single crystals via some emerging strategies. Especially, the preparation, properties, structural factors, importance, advantages, and potential applications of polymer single crystals are presented.