Kevin De Bruycker

Rewritable Polymer Brush Micropatterns Grafted by Triazolinedione Click Chemistry

Triazolinedione (TAD) click reactions were combined with microcontact chemistry to print, erase, and reprint polymer brushes on surfaces. By patterning substrates with a TAD-tagged atom-transfer radical polymerization initiator (ATRP-TAD) and subsequent surface initiated ATRP, it was possible to graft micropatterned polymer brushes from both alkene- and indole-functionalized substrates. As a result of the dynamic nature of the Alder-ene adduct of TAD and indole at elevated temperatures, the polymer pattern could be erased while the regenerated indole substrate could be reused to print new patterns. To demonstrate the robustness of the methodology, the write-erase cycle was repeated four times.

Recyclable cross-linked hydroxythioether particles with tunable structures via robust and efficient thiol-epoxy dispersion polymerizations

The highly efficient base-catalyzed thiol-epoxy reactions were exploited in dispersion polymerizations as a simple method for the preparation of uniform and cross-linked particles with a tunable size, glass transition temperature (Tg) and network structure. Particles with sizes ranging from 1 μm to 3 μm could be obtained by varying monomer concentration and reaction medium, while the Tgs could be increased from −10 °C to 65 °C by adjusting the monomer functionality and structure. In order to further demonstrate the potential of these particles, the thioether bonds were simply oxidized to sulfoxides and sulfones to increase the Tgs and stiffness of the particles significantly. Moreover, the cross-linked particles proved to be reprocessable to a polymer material when a proper catalyst was incorporated. We believe that this simple and efficient method will become a powerful tool for particle preparation, and paves the way for polymer particle reinforcement and recycling.

Covalent Fluorination Strategies for the Surface Modification of Polydienes

Nonreactive additives are widely applied to enhance polymer properties but can leach out of the material over time. In this work, two essentially different fluorinated additives bearing a triazolinedione moiety are synthesized and grafted on several polydiene backbones (acrylonitrile-butadiene-styrene, styrene-butadiene, and styrene-isoprene-styrene (SIS) copolymers), either by dip-coating or by reaction in solution. The resulting polymers are analyzed by contact angle goniometry, size exclusion chromatography, and NMR, infrared, and X-ray photoelectron spectroscopy. Independent of the modification procedure, the fluorophilic perfluoroalkyl additive is found at the material surface, thereby yielding a more hydrophobic surface. For SIS thermoplastic elastomers, for example, contact angles up to 125° can be obtained.

Ultrafast Tailoring of Carbon Surfaces via Electrochemically Attached Triazolinediones

The straightforward coupling between a triazolinedione (TAD) unit and citronellyl derivatives via an Alder-ene reaction has been exploited to tailor the physicochemical surface properties of glassy carbon (GC) surfaces in an ultrafast and additive-free manner. For this purpose, we first covalently grafted a TAD precursor onto GC via electrochemical reduction of an in situ generated diazonium salt, which was then electrochemically oxidized into the desired GC-bonded TAD unit. A kinetic study of the modification of this reactive layer with an electroactive ferrocene probe proved that a complete functionalization was obtained in merely 1 minute. Further modification experiments with a fluorinated probe demonstrated that the surface properties can be swiftly tailored on demand. The different modification steps, as well as the efficiency of this strategy, were investigated by electrochemistry, contact angle goniometry, and X-ray photoelectron spectroscopy analysis.