The capability of a polymer to depolymerize, regenerating its original monomer for further polymerization, is very attractive in terms of sustainability. Recently discovered sugar poly(orthoesters) are an important class of glycopolymer. The high sensitivity of the backbone orthoester linkage toward acidolysis provides a valuable model to study the depolymerization. Herein, a sugar poly(orthoester) is shown to be completely depolymerized under acidic conditions. Interestingly, instead of the original monomer, the depolymerization gave a stable cyclic product (1,6-anhydro glucopyranose) in most cases, which was kinetically and thermodynamically favored. However, this pathway could be inhibited by chemically deactivating a key intermediate and thus favoring the formation of the original monomer. Efficient repolymerizaton of the regenerated monomer is also demonstrated.

The Front Cover shows that a glycopolymer undergoing a cycle of depolymerization and repolymerization. In their Communication, the authors reversibly depolymerized a sugar poly(orthoester) under acidic conditions, demonstrating that regeneration of the monomer is possible. More information can be found in the Communication by Li et al. on page 4829 in Issue 24, 2017 (DOI: 10.1002/cssc.201701870).

Invited for this month′s cover is the group of Wenjun Du at Central Michigan University. The Cover Picture shows a glycopolymer undergoing a cycle of depolymerization and repolymerization. The Communication itself is available at 10.1002/cssc.201701870.