The role of functional monomers on producing nanostructured lattices obtained by surfactant-free emulsion polymerization – A Novel Approach

A. Marim Oliveira, K. Lanigra Guimarães, N. Neto Pereira Cerize
INSTITUTE FOR TECHNOLOGICAL RESEARCH, BR

Keywords: latex, emulsion polymerization, nanoparticle, silica, MMA

Summary:

Nanostructured lattices were prepared in a one-step emulsion polymerization reaction in the absence of surfactants by exploring the so called “pickering” stabilization mechanism. The synthesis protocol and the properties of particles were evaluated with special emphasis to the chemical properties of the functional monomers. Colloidal silica was used to ensure the physical stability required to produce nanoparticles as a result of the emulsion polymerization route. Three different monomers (methylmetacrylate, styrene and vinyl acetate)and four different functional polymers (acrylic acid, styrene-sulfonate, hydroxyethylmethacrylate, dymethylaminoethyl methacrylate) were evaluated. The obtained lattices were characterized regarding to surface tension, particle size, morphology, viscosity, zeta potential and colloidal stability. The one-step pickering emulsion polymerization proved to be an effective approach to prepare lattices of industrial interest without the use of surfactants. The obtained particles presented average mean diameters ranging from 155 to 345 nm with relatively low polidispersity indices. The most promising behavior was experimentally verified once selecting the styrene-sulfonate as the functional monomer. The hydroxyethylmethacrylate also proved to be an interesting alternative although its limitation related to high surface tension applications. The high resolution images registered explicit morphological aspects that effectively contribute to elucidate the “pickering” stabilization mechanism and the resultant core-shell structure derived thereof.