Radical Mediated Thiol-Ene Emulsion Polymerizations

Abstract

Radical mediated thiol−ene emulsion polymerizations for the synthesis of aqueous dispersion of polymer particles with narrow particle size distributions are reported. Submicrometer polymer particles comprising of cross-linked or linear chains were obtained using a water-soluble thermal initiator, without the need for a high-intensity emulsification step. Particles were prepared using 1,3,5-triallyl-1,3,5-triazine-2,4,6­(1H,3H,5H)-trione, pentaerythritol tetrakis­(3-mercapto­propionate), trimethylol­propane diallyl ether, 1,6-hexane­dithiol, and 3,6-dioxa-1,8-dithiooctane monomers. Potassium persulfate was used as the water-soluble initiator, and sodium dodecyl sulfate was used as the surfactant. The effects of surfactant, initiator, and comonomer concentrations on the particle diameters in the emulsion polymers are reported. The order of dependence of particle diameter on the surfactant concentration was −(0.44 ± 0.03) and on the initiator concentration was −(0.53 ± 0.04). The particle size distributions in the cross-linked latexes were generally broad. A seeded emulsion polymerization reaction, consisting of delayed addition of the cross-linker, was found to result in cross-linked thiol–ene latexes with narrow particle size distribution.

Polymer micro-particles formed by thiol–ene suspension polymerization using canola oil as a diluent solvent

“…Recent work has shown the viability to use thiol-ene systems via either suspension or emulsion polymerizations to create particles with controllable sizes. [11][12][13][14][15][16] Durham et al were the first to show that a waterborne photopolymerization reaction could occur between a multifunctional alkene and thiol monomers to create particles. They used a suspension polymerization with sodium dodecyl sulfate (SDS) surfactant to react a 3-functional alkene to a 4-functional thiol with toluene or chloroform as the diluent.…”

Composite Particles From Pickering‐Stabilized Radical Mediated Thiol‐Ene Suspension Polymerizations

“…Previously, we and others developed radical‐mediated thiol‐ene and thiol‐yne polymerizations for the production of colloidal polymer particles . Synthesis of colloidal polymers have been shown to work in different dispersed polymerization modes, such as emulsions, dispersions, miniemulsions and suspensions . In these prior cases, the particles were emulsified or stabilized using common surfactants, such as sodium dodecyl sulfate (SDS), or natural gums .…”

TEMPO Driven Mild and Modular Route to Functionalized Microparticles

“…It was possible to obtain various morphologies, for example, core–shell, dimple‐, or bulge‐patched particles due to phase separation between thiol‐ene polymer and polystyrene. Durham et al utilized radical mediated thiol‐ene emulsion polymerization for the synthesis of crosslinked polymeric particles. They studied the influence of the concentration of the surfactant, the initiator and the comonomers on the particle size obtained.…”