Single crystal polymers have unique applications in various fields Compared to single crystals of small molecules. Because of the long chain and various conformation, it is hard for the polymers to be crystallized directly from solution. Few examples of polymer single crystals prepared in this way suffered from low quality and small size. Topochemical polymerization provides a potential solution to yield high-quality polymer single crystals.
If the polymer is still mono crystalline, the transformation from single-crystal monomer to polymer is called single-crystal-to-single-crystal (SCSC) transformation, which required a more sophisticated design than normal topochemical polymerization. In order to prevent the polymer from breaking into polycrystalline powder, the stress-releasing strategies should be carefully considered. However, the study on general criteria of SCSC transition is still in its infancy and requires further study.