Dynamic structures containing polymers are considered a new class of polymeric materials with very attractive properties, since they can behave as thermosets at room temperature but at the same time they can be reprocessed to any shape. Recently, aromatic disulfides have been explored as dynamic bonds because of their good exchange reaction rate at low temperatures. In this work, we explore the utilization of aromatic diselenides on the basis of their lower bond energies in comparison with their disulfide counterparts. By comparing a model exchange reaction between aromatic diselenides and aromatic disulfides, the ability of aromatic diselenides to exchange faster than aromatic disulfides has been demonstrated. These results are supported by molecular quantum chemical calculations, confirming the faster exchange of aromatic diselenides in comparison with disulfides. In addition, a [2 + 1] radical-mediated reaction mechanism is proposed for aromatic diselenides to understand their faster kinetic exchange. An aromatic diselenide has been incorporated into polyurethane networks using a para-substituted amine diphenyl-diselenide. The resulting materials not only exhibit faster self-healing properties than the corresponding disulfide based materials, but also show the ability to be processed at temperatures as low as 100 °C. The fact that aromatic amines are already used as crosslinkers in a wide range of commercial products makes this system very attractive.

Due to their unique properties, selenium-containing polymers have become one of the research focuses of polymer materials in recent years. First, selenium can transform among various states of selenoxide, selenone, and selenium free radicals, and then be restored under these conditions, which endows these polymers with multiresponsive behaviors, including responses to redox changes, light, radiation, etc. Second, these polymers show characteristic properties. Selenium-containing polymers exhibit unique multiple optical–electrical characteristics, including high photoconductivity, anisotropic thermoconductivity, high piezoelectric and thermoelectric responses, and a high refractive index. Based on these various properties, selenium-containing polymers are regarded as excellent functional polymer materials. Therefore, it is meaningful to synthesize selenium-containing polymers with various structures. This paper principally gives a summary of the organic reactions of organoselenium compounds and reviews the research on the synthesis of selenium-containing polymers via different methods, such as the use of selenium-containing monomers and their polymerization, selenium-containing initiators for polymerization, selenium-containing mediators for controlled polymerization and selenium-containing molecules for the postmodification of polymers. Moreover, applications of selenium-containing polymers are described, including their use as intrinsic high refractive index polymeric materials, oxidative- and reductive-responsive materials, dynamic exchanging polymers, selective metal adsorbents, and catalysts.

Background: Multifunctional hydrogels with controllable degradation and drug release have attracted extensive attention in diabetic wound healing. This study focused on the acceleration of diabetic wound healing with selenide-linked polydopamine-reinforced hybrid hydrogels with on-demand degradation and light-triggered nanozyme release. Methods: Herein, selenium-containing hybrid hydrogels, defined as DSeP@PB, were fabricated via the reinforcement of selenol-end capping polyethylene glycol (PEG) hydrogels by polydopamine nanoparticles (PDANPs) and Prussian blue nanozymes in a one-pot approach in the absence of any other chemical additive or organic solvent based on diselenide and selenide bonding-guided crosslinking, making them accessible for large-scale mass production. Results: Reinforcement by PDANPs greatly increases the mechanical properties of the hydrogels, realizing excellent injectability and flexible mechanical properties for DSeP@PB. Dynamic diselenide introduction endowed the hydrogels with on-demand degradation under reducing or oxidizing conditions and light-triggered nanozyme release. The bioactivity of Prussian blue nanozymes afforded the hydrogels with efficient antibacterial, ROS-scavenging and immunomodulatory effects, which protected cells from oxidative damage and reduced inflammation. Further animal studies indicated that DSeP@PB under red light irradiation showed the most efficient wound healing activity by stimulating angiogenesis and collagen deposition and inhibiting inflammation. Conclusion: The combined merits of DSeP@PB (on-demand degradation, light-triggered release, flexible mechanical robustness, antibacterial, ROS-scavenging and immunomodulatory capacities) enable its high potential as a new hydrogel dressing that can be harnessed for safe and efficient therapeutics for diabetic wound healing.