Helically twining polymerization for constructing polymeric double helices

Abstract

The double helix is one of the most basic and exquisite architectures in nature, and thus has received much attention in multiple disciplines. However, the types of artificial polymeric double helices and their synthetic methods are severely limited. The present contribution develops a novel 3-step methodology for preparing double helices consisting of helical substituted polyacetylenes (DHSPs): (1) an optically inactive helical polymer is synthesized using an achiral monomer; (2) the as-obtained polymer is induced to form a one-handed helix by “locking” a chiral monomer in the helical grooves; (3) the “locked” chiral monomer undergoes helically twining polymerization along the pre-formed one-handed helical polymer chains, thereby constructing the DHSPs. Circular dichroism and UV-vis absorption spectra in combination with high resolution TEM images demonstrate the optical activity, double helical structure, and helix sense of the DHSPs. The convenient synthetic strategy is expected to provide various kinds of double helical polymers.