Atom Transfer Radical Polymerization in Aqueous Media Using Different Water-Soluble Initiators and Ligands

Abstract

Abstract: Styrene and methyl methacrylate have been polymerized successfully through atom transfer radical polymerization (ATRP) in aqueous dispersed media (emulsion ATRP). The thesis is divided into four experimental parts. In the first part, a water-soluble initiator was prepared for emulsion ATRP and utilized under various conditions in the presence of two ligands N, N, N’, N’’, N’’-Pentamethyldiethylenetriamine and 2,2’-bipyridine to attain activation/deactivation only in the oil phase with Tween 20 as a non-ionic surfactant. The initiator was synthesized by the reaction of diethanolamine with α-Bromoisobutyryl bromide in anhydrous tetrahydrofuran. 1H NMR spectroscopy (500 MHz, deuterium oxide, or chloroform-d) was performed to confirm the successful synthesis of the initiator and polystyrenes. In the second and third parts, two commercial initiators were used, poly(ethylene glycol) methyl ether 2-bromoisobutyrate (Mn= 2000 g/mol), and 2-hydroxyethyl 2-bromoisobutyrate (Mn= 211.05 g/mol). BPY, tris(2-pyridylmethyl) amine and 4, 4’-dinonyl -2, 2’-dipyridyl were used as the ligands with various molar ratios. Polyoxyethylene (80) sorbitan monooleate, and polyoxyethylene (20) oleyl ether were used as non-ionic surfactants. In the fourth part, a macroinitiator was synthesized by the reaction of polyoxyethylene (20) stearyl ether with α-Bromoisobutyryl bromide. The formation of the macroinitiator as well as the successful synthesis of poly(ethylene glycol)-b-polystyrene, and poly(ethylene glycol)-b-poly(methyl methacrylate) block copolymers were confirmed by Fourier transform infrared and 1H NMR spectroscopies. The molecular weight of the resulting polymers, as well as the stability of the emulsion systems, were evaluated by gel permeation chromatography and dynamic light scattering, respectively.