Polymer Nanoparticles with Activated Ester Surface by Using Functional Surfmers

Two new polymerizable surfactants (surfmers), p‐[11‐(acrylamido)‐undecanoyloxy]phenyldimethylsulfonium methylsulfate (AUPDS) and p‐[11‐(methacrylamido)undecanoyloxy]phenyldimethylsulfonium methylsulfate (MUPDS), were synthesized and used for the preparation of functional polymer nanoparticles. The surfmers were characterized (cmcAUPDS = 6.0 ± 0.2 mmol · L−1; cmcMUPDS = 3.2 ± 0.2 mmol · L−1) and employed in emulsion polymerization with methyl methacrylate as a comonomer. Depending on the surfmer‐to‐comonomer ratio, the resulting particles had a dynamic light scattering diameter between 109 nm and 167 nm. Scanning electron microscopy confirmed a very narrow size distribution. The particles showed a ζ‐potential of 20 to 24 mV as measured by micro‐electrophoresis, corresponding to the electrostatic stabilization by the positively charged sulfonium group of the surfmer. The reactivity of the particle bound active ester was determined by titration of the latex with a fluorescent probe and subsequent fluorescence analysis. 6‐Aminofluoresceine was immobilized from 0.8 μmol to 9.6 μmol per 1 g particles depending on the AUPDS starting concentration in emulsion polymerization. Scanning electron microscopy images of poly(MMA‐co‐AUPDS) particles (sample PA 6, 0.25 mol‐% AUPDS) showing the narrow size distribution over a larger sample area.