Self‐Assembling Supramolecular Hybrid Hydrogel Beads

Abstract With the goal of imposing shape and structure on supramolecular gels, we combine a low‐molecular‐weight gelator (LMWG) with the polymer gelator (PG) calcium alginate in a hybrid hydrogel. By imposing thermal and temporal control of the orthogonal gelation methods, the system either forms an extended interpenetrating network or core–shell‐structured gel beads—a rare example of a supramolecular gel formulated inside discrete gel spheres. The self‐assembled LMWG retains its unique properties within the beads, such as remediating PdII and reducing it in situ to yield catalytically active Pd0 nanoparticles. A single PdNP‐loaded gel bead can catalyse the Suzuki–Miyaura reaction, constituting a simple and easy‐to‐use reaction‐dosing form. These uniquely shaped and structured LMWG‐filled gel beads are a versatile platform technology with great potential in a range of applications.


S4 Infrared (IR) spectroscopy
Xerogel samples for infrared were prepared by removing the solvent from the gels under high vacuum. A small amount of the resulting powder was placed into the infrared spectrophotometer and the spectra recorded in the range of 450-4000 cm -1 .

S5 Optical microscopy
Optical microscopy images were collected on a Zeiss stereo microscope. The gel beads were either analysed as such or pre-embedded into resin. These last samples were dehydrated through an ethanol series, then embedded in LR white resin. Sections were 1 m thick. Once the section was dried on the slide, it was stained with Toluidine Blue (0.6% with 0.3% Na2CO3). All the gel beads were prepared using 20 L volumes (unless otherwise specified) using 0.3% wt/vol of DBS-CONHNH2 and 0.5% wt/vol of alginate ( Figure S4).  coloured with toluidine blue. Note core shell morphology and fibrillar interior. Scale bar: 1 mm. Figure S7. Cross-section of alginate gel bead embedded in resin and coloured using toluidine blue.

S7 Thermal stability studies
All the gels for Tgel determination were prepared as described in Section S2 in 2 mL vials (diameter: 1 cm, height: 4 cm). All the gels were placed in a high precision thermoregulated oil bath with an initial temperature of 25°C. The temperature was increased by 1°C/ min until 100°C. Every minute the gels were checked by tube inversion method and Tgel was considered as the temperature at which the gel began to run down the sides of the vial. These experiments were performed in triplicate to ensure reproducibility and the average is reported. Errors are estimated at ±2°C. Table S1. Tgel values of gels formed by individual gelators and the DBS-CONHNH2/alginate multicomponent gel (interpenetrating networks).

S8 Rheology
Gel samples for rheology were prepared as described in Section S2 using bottomless vials as templates to obtain the intended gel dimensions. The measurements were carried out at 25°C using a 20 mm parallel plate and a gap of 2 mm. To avoid solvent evaporation and keep the sample hydrated, a solvent trap was used, and the internal atmosphere was kept saturated. Amplitude sweep experiments were performed in the range of 0.05-100% strain at a 1 Hz frequency to identify the linear viscoelastic region. Frequency sweep experiments were performed between 0.1 and 100 Hz using a shear strain of 0.25%. The measurements were repeated three times to ensure reproducibility and the average data are shown.

S9.1 Uptake Studies by UV-Vis Spectroscopy
Uptake of Pd(II) onto DBS-CONHNH2/alginate multicomponent gels was monitored by UV-VIS spectroscopy and the residual concentration was calculated from the calibration curve plotted for UV-VIS absorption of PdCl2 at λmax= 425 nm. suspended in water (0.5 mL), 0.5 mL of alginate (1% wt/vol) and 1 mL of CaCl2 (5% wt/vol). The excess of CaCl2 solution was then removed and the gels were washed with water multiple times.
Each of these gels was immersed in 3 mL of PdCl2 solution (approx. 5 mM, the precise concentration was determined by UV before Pd uptake) and left to interact. At specified times, the solutions were analysed by UV and then transferred back to the gels. S16