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 (cmc(AUPD) = 6.0 +/- 0.2 mmol.L-1; cmc(MUPDS) = 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 zeta-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 mumol 9.6 mumol per 1 g particles depending on the AUPDS starting concentration in emulsion polymerization.