Solid-State Synthesis of Two Different Polymers in a Single Crystal: A Miscible Polymer Blend from a Topochemical Reaction.

The topochemical synthesis of a miscible polymer blend is described. The azide- and alkyne-decorated tetrol 1 crystallizes as two different conformers. Both conformers exhibit self-sorted head-to-tail alignment with proximally placed reacting groups such that topochemical polymerization yields two types of polymer chains, each containing only one type of conformer. The orientation of complementary reactive groups in one of the head-to-tail-arranged conformers favors the formation of cis-triazole linkages, and the other favors the trans-triazole linkages. Crystals of 1 on heating gave a perfect polymer blend containing equal amounts of cis-triazole-linked and trans-triazole-linked polymers. As each conformer is H-bonded to four conformers of the other kind, the polymerization yields a perfect polymer blend wherein each polymer chain is surrounded by chains of the other type. Thus, the molecular ordering in the prepolymerized state in a crystal is utilized to create a polymer blend.