Self-immolative polymers (SIPs) are promising members of the emerging class of recyclable polymers with the ability to end-to-end depolymerize to their monomers. Unfortunately, SIPs are often synthesized by cumbersome procedures at low temperatures in protected atmosphere. In this study, a SIP with a novel poly­(disulfide) backbone is introduced, using dl-dithiothreitol (DTT) as the monomer. Remarkably, poly­(DTT) can be produced by solid-state polymerization in a robust and easily scalable process by mechanically mixing DTT with 2,2′-dithiodipyridine as the end-capping agent. The new polymer possesses good thermal and chemical stabilities, but once its depolymerization is triggered, this proceeds smoothly within minutes to afford cyclic DTT because of a favorable intramolecular back-biting thiol–disulfide exchange reaction in the polymer backbone. As a proof of concept, the cyclic DTT waste was recovered, reduced to DTT monomer, and repolymerized in a closed-loop approach.

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It is well known that strontium (Sr) has a significant effect on peri-implant bone healing when administered systemically. Due to the risk of adverse effects of such treatments, new routes focusing on the local, sustained release of Sr from bone–implant contact surfaces have been explored, with success in in vivo experiments. However, the increase of Sr concentrations in the peri-implant bone has not been described in depth yet. Here, we show that a local, sustained Sr release from Ti–Sr–O physical vapor deposition (PVD) coatings by magnetron sputter coating increases the Sr/Ca ratio close to the implant in a rabbit model and that the Sr/Ca background level is reached approximately 500 μm from the implant.