The non-polar nature of polyolefins, alongside providing the valuable properties that mark them as one of the most important modern polymers, also entails that their application in standard processes such...

Radical ring‐opening polymerization (rROP) of cyclic ketene acetals (CKAs) combines the advantages of both ring‐opening polymerization and radical polymerization thereby allowing the robust production of polyesters coupled with the mild polymerization conditions of a radical process. rROP was recently rejuvenated by the possibility to copolymerize CKAs with classic vinyl monomers leading to the insertion of cleavable functionality into a vinyl‐based copolymer backbone and thus imparting (bio)degradability. Such materials are suitable for a large scope of applications, particularly within the biomedical field. The competition between the ring‐opening and ring‐retaining propagation routes is a major complication in the development of efficient CKA monomers, ultimately leading to the use of only four monomers that are known to completely ring‐open under all experimental conditions. In this article we investigate the radical ring‐opening polymerization of model CKA monomers and demonstrate by the combination of DFT calculations and kinetic modeling using PREDICI software that we are now able to predict in silico the ring‐opening ability of CKA monomers.

The incorporation of heteroatoms into the backbone of commodity polymers prepared by radical polymerization is an elegant way to confer (bio)degradability to such materials. This could be achieved via the radical ring-opening polymerization of cyclic monomers. Thionolactones were recently identified as promising comonomers for rROP but only reacting with activated monomers such as acrylate and acrylamide derivatives. Herein, we describe two thionolactone monomers, oxepane-2-thione i.e. εthiono-caprolactone (thCL) and 7-butyloxepane-2-thione, i.e ε-thiono-decalactone (thDL) capable of performing radical ringopening polymerization with less activated monomers such as vinyl acetate (VAc) to produce readily degradable copolymers via the insertion of thioester containing repeating units. A thorough mechanistic investigation was performed to understand the reactivity of the two cyclic monomers. We identified the initiation as the main parameter to perform the polymerization of such thionolactone monomers. In a specific case the poly(ε-thCL) homopolymer was successfully obtained. Concerning the copolymerization with vinyl acetate, a variety of polymerizations with differing feed ratios were performed, and the degradability of the copolymers via aminolysis examined by SEC. To demonstrate the usefulness of thionolactones a variety of block copolymers containing thioester linkages involving N,N-dimethylacrylamide and VAc were also prepared and degraded.