In the current work, we report our findings on the use of radical thiol-ene chemistry for polymerpolymer conjugation. The manuscript combines the results from the Preparative Macromolecular Chemistry group from Karlsruhe Institute of Technology (KIT) and the Polymer Chemistry Research group from Ghent University (UGent), which allowed for an investigation over a very broad range of reaction conditions. In particular, thermal and UV initiation methods for the 2 radical thiol-ene process were compared. In the KIT group, the process was studied as a tool for the synthesis of star polymers by coupling multi-functional thiol core molecules with poly(nbutyl acrylate) macromonomers (MM), employing thermally decomposing initiators. The product purity and thus reaction efficiency was assessed via electrospray ionization mass spectrometry. Although the reactions with 10 or 5 equivalents of thiol with respect to macromonomer were successful, the coupling reaction with a one-to-one ratio of MM to thiol yielded only a fraction of the targeted product, besides a number of side products. A systematic parameter study such as a variation of the concentration and nature of the initiator and the influence of thiol to ene ratio was carried out for a one-to-one ratio of MM to thiol content.Further experiments with poly(styrene) and poly(isobornyl acrylate) containing a vinylic end group confirmed that thermal thiol-ene conjugation is far from quantitative in terms of achieving macromolecular star formation. In parallel, the UGent group has been focusing on photo-initiated thiol-ene chemistry for the synthesis of functional polymers on the one hand and block copolymers consisting of poly(styrene) (PS) and poly(vinyl acetate) (PVAc) on the other hand.Various functionalization reactions showed an overall efficient thiol-ene process for conjugation reactions of polymers with low molecular weight compounds (~90% coupling yield). However, while SEC and FT-IR analysis of the conjugated PS-PVAc products indicated qualitative evidence for a successful polymer-polymer conjugation, 1 H NMR and elemental analysis revealed a low conjugation efficiency of about 23% for a thiol-to-ene ratio equal to one. Blank reactions using typical thiol-ene conditions indicated that bimolecular termination reactions 3 occur as competitive side reactions explaining why a molecular weight increase is observed even though the thiol-ene reaction was not successful. The extensive study of both research groups indicates that radical thiol-ene chemistry should not be proposed as a straightforward conjugation tool for polymer-polymer conjugation reactions. Head-to-head coupling is a major reaction pathway, which interrupts the propagation cycle of the thiol-ene process.

Thiol-ene and thiol-yne reactions (thio-click) are explored as efficient pathways towards rapid production of diverse monodisperse macroporous and nonporous functional beads. In a straightforward method, polymer beads containing amine, hydroxyl and carboxyl groups have been prepared by reacting a tetrafunctional thiol with a range of mono and/or multifunctional -enes/-ynes containing the desired functional groups. The 'thio-click' reaction has been performed in a simple home-made microfluidic device utilizing thiol and ene/yne monomers at a 1:1 ratio of thiol to π-bond. The porous functional beads were prepared making use of a porogen in combination with a photoinitiator. The optical and scanning electron microscopy images demonstrated monodispersity of the beads with a spherical shape ranging in size from 210 to 600 µm. The beads were characterized in terms of glass transition temperature, surface area measurement and composition. The accessible amine and hydroxyl loading in the beads ranges between 0.2 to 0.7 mmol/g, as determined by the Fmoc method. This work demonstrates the applicability of 'thio-click' reactions in microfluidics as a powerful tool for the rapid design of functional beads for diverse applications.

Beads labelled using surface enhanced resonance Raman scattering (SERRS) are highly sensitive and specific tags, with potential applications in biological assays, including molecular diagnostics. The beads consist of a nucleus containing dye labelled silver-nanoparticle aggregates surrounded by a polymer core. The nuclei generate strong SERRS signals. To illustrate the coding advantage created by the sharp, molecularly specific SERRS signals, four specially designed SERRS dyes have been used as labels and three of these have been combined in a multiplex analysis. These dyes use specific groups such as benzotriazole and 8-hydroxyquinoline to improve binding to the surface of the silver particles. The aggregation state of the particles is held constant by the polymer core, this nucleus also contains many dye labels, yielding a very high Raman scattering intensity for each bead. To functionalise these beads for use in biological assays an outer polymer shell can be added, which allows the attachment of oligonucleotide probes. Oligonucleotide modified beads can then be used for detection of specific oligonucleotide targets. The specificity of SERRS will allow for the detection of multiple targets within a single assay.

Thiol- and yne-functionalized beads were manufactured in a simple microfluidic setup. While CuAAC and thiol-yne reactions were performed on yne-functionalized beads, 9 different thiol-X reactions were compared, in terms of kinetics and conversion, on thiol-functionalized beads.

This article aims to present, adapt, and propose the use of the Balanced Scorecard (BSC) as a tool to support strategic management for sustainable cities. To achieve this goal, publications and 27 sustainable cities projects were also consulted, through project reports and programs from the cities themselves on the topic were consulted. A text mining analysis was applied to the results obtained in this literature review to find the main factors related to sustainable cities. To evaluate the findings of this first stage, consultations with specialists were carried out, specifically to assess the main factors. Based on the previous steps, and based on the original BSC, an adaptation of the tool was proposed, where its structure was changed to meet the needs of the strategic management of sustainable cities. It was concluded that creating a sustainable city requires understanding the difficulties faced by urban center managers with the implementation and management of institutional sustainable development practices. The BSC for sustainable cities can assist as a viable management strategic tool to more efficient use of resources in order to develop sustainable cities.