Crosslinked Microgels as Platform for Hydrolytic Catalysts

In an effort to develop biomimetic glycosyl transfer catalysts, a polymerization protocol was developed that is applicable to the synthesis of crosslinked microgels via UV-initiated free radical polymerization of miniemulsions at ambient temperature and below. The catalytic activity of the microgels derived from butyl acrylate, EGDMA, and a catalyst-precursor ligand was established using the hydrolysis of 4-methylumbelliferyl β-d-galactopyranoside as a model reaction. The microgel-catalyzed hydrolysis was up to 3 × 10⁵-fold accelerated over the background reaction and notably 38-fold faster than the hydrolysis catalyzed by its low molecular weight analog. Dynamic light scattering analysis demonstrated mean hydrodynamic diameters of the particles between 210 and 280 nm and chemical stability of the particles in aqueous solution between pH 1 and 13. A bell-shaped correlation between catalytic proficiency and material rigidity was observed that peaks at 40 mol % of crosslinking content of the microgel.