Surface etching of methacrylic microparticles via basic hydrolysis and introduction of functional groups for click chemistry

[Display omitted] ► Basic hydrolysis of methacrylic particles leads to carboxylic surface groups. ► Only the particles’ surface was activated without altering the particles’ core. ► Azides, thiols, and alkynes were introduced for subsequent click reactions. Controlled basic hydrolysis of poly(methyl methacrylate-co-ethylene glycol dimethacrylate) P(MMA-co-EGDMA) microparticles with a diameter d50=6μm led to high densities of carboxylic groups at the particles’ surface of up to 1.288μeqg−1 (equivalent to 1.277μmolm−2). The microparticles’ core has not been altered by this surface activation procedure as seen by fluorescent staining. The kinetics of the hydrolysis reaction was investigated via electrophoretic light scattering and particle charge detection employing polycation titration under shear condition. The activated microparticle’s surface was subsequently exploited in carbodiimide-mediated coupling reactions using a variety of molecular reactants, that is, 11-azido-3,6,9-trioxaundecan-1-amine, cysteamine, propargylamine, and fluoresceinamine, thus enabling the introduction of chemically reactive moieties such as azides, thiols, and alkynes. Fluorescent staining of the particles’ surface successfully demonstrated the versatile applications of surface functionalized microparticles via copper-catalyzed huisgen cycloaddition. Carrying on this two-step procedure in a controlled manner provides an excellent way for relatively simple but highly effective surface functionalization.