Papers Published

  1. Ogawa, Katsu and Chemburu, Sireesha and Lopez, Gabriel P. and Whitten, David G. and Schanze, Kirk S., Conjugated polyelectrolyte-grafted silica microspheres, LANGMUIR, vol. 23 no. 8 (April, 2007), pp. 4541--4548 [doi] .
    (last updated on 2010/02/08)

    A direct method for preparation of conjugated polymer-grafted silica particles is reported. Silica particles (0.3 and 5 mu m diameter) are treated with a 3-(trimethoxysilyl)propylamine derivative that is functionalized with an aryl iodide unit. A solution step-growth polymerization reaction is performed in solution that contains a dispersion of the aryl iodide-functionalized particles. The reaction is a Pd(0)-catalyzed (Sonogashira) A-B-type polymerization of an oligo(ethylene glycol)-fuctionalized diiodobenzene and a bis(propyloxy)sulfonate-substituted diethynylbenzene. The overall process affords silica particles that feature a surface graft layer of an anionic poly(phenylene ethynylene)-type conjugated polyelectrolyte. The particle surface modification process was monitored by infrared (FTIR) spectroscopy, and the polymer-grafted silica particles were characterized by thermogravimetric analysis, scanning and transmission electron microscopy, confocal fluorescence microscopy, and absorption and fluorescence spectroscopy. The conjugated polyelectrolyte-grafted silica particles are highly fluorescent, and a Stern-Volmer quenching study of the particles' fluorescence with electron-transfer- and energy-transfer-type quenchers shows that the quenching response depends on the type of quenching mechanism.