End-of-life tires are utilized for various purposes, including sports pitches and playground surfaces. However, several substances used at the manufacture of tires can be a source of concerns related to human health or environment’s adverse effects. In this context, it is necessary to map whether this approach has the desired effect in a broader relation. While the negative effects on human health were investigated thoroughly and legislation is currently being revisited, the impact on aquatic or soil organisms has not been sufficiently studied. The present study deals with the exposure of freshwater and soil organisms to rubber crumb using the analysis of heavy metal and polycyclic aromatic hydrocarbon concentrations. The obtained results refer to substantial concerns related to freshwater contamination specifically, since the increased concentrations of zinc (7 mg·L⁻¹) and polycyclic aromatic hydrocarbons (58 mg·kg⁻¹) inhibit the growth of freshwater organisms, Desmodesmus subspicatus, and Lemna minor in particular. The performed test with soil organisms points to substantial concerns associated with the mortality of earthworms as well. The acquired knowledge can be perceived as a roadmap to a consistent approach in the implementation of the circular economy, which brings with it a number of so far insufficiently described problems.

The design, synthesis, and comprehensive characterization of six novel halogenated azobenzene acrylate monomers bearing fluorine, chlorine or bromine substituents is reported. The monomers were prepared via a facile three-step synthetic route involving azo-coupling, O- alkylation and O -acylation. Apart from the steady electrochemical properties, halogen substitution proved to be a very useful tool to tune the thermal and optical properties, light-induced switching in particular. Monohalogen derivatives exhibited up to 93% E → Z photoconversion efficiency in solution, whereas the efficiency of dihalogen analogues is lower by 20%, which is ascribed to their nonplanar arrangement. Kinetics studies identified the most stable Z -isomer of the difluoro derivative ( τ _1/2 = 3.74/6.59 h at 60 °C in DCE/CDCl ₃ ). The monofluoro derivative embedded in a polystyrene film demonstrated photoresponsive behavior and remarkable stability by maintaining a macroscopically visible color change for over 90 days. These findings demonstrate that ortho -halogenation is a powerful tool for tuning the properties of photoresponsive materials for potential applications in colorimetric thermal sensing and light-controlled functional systems.