Characterization

¹H (360 MHz) and ¹³C (90 MHz) NMR spectra were recorded on a Bruker Avance III spectrometer in dimethylsulphoxide (DMSO)-d6.¹H NMR coupling constants are given in Hz. ¹H NMR spectra were referenced against the signal of residual DMSO at 2.50 p.p.m. and ¹³C NMR spectra were referenced against the DMSO-d6 signal at 39.52 p.p.m. TGAs were conducted under N₂ using a Mettler-Toledo STAR thermogravimetric analyser in the range of 25–500 °C with a heating rate of 10 °C min⁻¹. DSC measurements were performed under N₂ using a Mettler-Toledo STAR system operating at a heating/cooling rate of 10 °C min⁻¹ in the range −70 to 150 °C, unless indicated otherwise. Data from the second heating cycle and the reverse heat flow curve are reported unless indicated otherwise (T_g=glass transition temperature). DMAs were performed on a TA Instruments DMA Q800 with a heating rate of 5 °C min⁻¹ and a frequency of 1 Hz in the range of −50 to 140 °C using a three-point bending setup. Three-point bending tests were conducted on the same instrument at 25 °C, with a displacement rate of 100 μm min⁻¹. All mechanical tests were conducted on rectangular samples (typical dimensions: 25 mm × 5 mm × 230 μm). Flexural moduli were determined from the entire curves, as all samples displayed a linear relation between stress and strain until failure. Load-sensing indentation measurements were performed using a CSM Ultra Nanoindenter equipped with a Berkovich tip (diamond). All experiments were performed using a loading and unloading rate of 100 μN min⁻¹, and 15 min of constant load (100 μN) before unloading to allow for creep deformation. AFM images and force spectroscopy measurements were performed on a JPK Nano Wizard II. AFM images were recorded with NanoWorld NCHR high-resonance frequency tips. Force spectroscopy tests were performed with a Bruker DNISP cantilever with a cube corner diamond tip (nominal sensitivity=249 N m⁻¹). Temperature-dependent AFM force spectroscopy tests were performed on coatings with a thickness of 300 μm on a thin round microscopy glass slide and placed on a JPK HTHS high-temperature heating stage, and the sample surface temperature was continuously monitored using a hand-held infrared camera. All recorded unloading curves were fitted (upper 50% of the unloading curve) and analysed according to the Oliver and Pharr model to yield the elastic modulus, assuming a Poisson ratio of 0.3 and a perfect cube corner tip³⁷. Rheological studies were performed on a TA instruments ARG2 Rheometer operating with a Peltier heating stage and parallel plate geometry. Ultraviolet–visible absorption spectra were measured on a Jasco V-670 spectrophotometer. Electrospray ionization mass spectrometry (ESI-MS) was measured by the Laboratory for Mass Spectroscopy of the University of Fribourg. Elemental analysis was performed by the Service d'analyses chimiques of the Ecole d'ingénieurs et d'architectes of Fribourg. FT-IR spectra were measured on a Perkin-Elmer Spectrum 65 spectrometer using dried (crystalline) powder in attenuated total reflection (ATR) mode between 800 and 4,000 cm⁻¹ with five accumulated scans per sample. Ultraviolet irradiation of the samples to achieve healing was performed with a Hoenle Bluepoint 4 Ecocure lamp connected to an optical fibre. An optical filter was used to irradiate limit the output to the wavelength range of 320–390 nm. The temperature increase during ultraviolet irradiation was monitored using an Optris PI connect infrared camera. Adhesion tests were performed by adhering two regular glass slides (overlapping area=10 × 25.7 mm²) with a thin layer of (UPyU)₃TMP). The adhesive properties were determined with a Zwick/Roell Z010 tensile tester at room temperature with a strain rate of 0.1 mm min⁻¹.