Emulsion copolymerization of vinyl acetate and butyl acrylate in the presence of fluorescent dyes

This article describes our first experiments for preparing dye-labeled latex particles by the emulsion copolymerization of a 4/1 (w/w) mixture of vinyl acetate-butylacrylate (VAc-BA). We discuss the synthesis of acrylate derivatives of phenanthrene, anthracene, and pyrene [9-acryloxymethyl phenanthrene (7), 9-acryloxymethyl-10-methyl anthracene (8), and 1-acryloxymethyl pyrene (10)] and an allyl ether derivative of anthracene [9-allyoxymethyl-10-methyl anthracene (9)]. Although the phenanthrene derivative 7 gave latex particles with high monomer conversion and good dye incorporation, the pyrene acrylate and both anthracene comonomers strongly inhibited the free-radical reaction. To assist our search for a dye that would serve as a useful energy acceptor for phenanthrene and without suppressing VAc-BA polymerization, we also examined batch emulsion polymerization in the presence of a variety of dye derivatives-substituted anthracenes, acridines, a coumarin, and two benzophenone derivatives. All of the anthracene derivatives, as well as aclidine, strongly inhibited monomer polymerization. The coumarin dye 7-hydroxy-4-methyl coumarin (22) that had only limited solubility allowed more than 90% monomer conversion. Most promising were 2-hydroxy-5-methyl benzophenone (23) and 4-NN-dimethylamino benzophenone (24) that at 1 mol % in the monomer mixture permitted virtually quantitative monomer conversion to latex. 4'-Dimethylamino-2-acryloxy-5-methyI benzophenone (25) copolymerized well with the VAc-BA mixture, yielding latex particles in high yield and with a narrow size distribution. These dyes appear to be useful acceptor dyes for energy-transfer experiments with phenanthrene. (C) 2002 Wiley Periodicals, Inc.