Investigation of AGET-ATRP of methyl methacrylate in surface-active ionic liquid microemulsions

Abstract

The first example of N-tetradecyl-N-methyl-2-pyrrolidonium was synthesized by using bromide as both an ionic liquid and a surfactant in ionic liquid-based microemulsion polymerization of methyl methacrylate under atom transfer radical polymerization at activator generated electron transfer conditions. The polymerization was carried out at room temperature using copper (II) chloride (CuCl2)/hexamethylene tetramine (HMTA) as a catalyst and CCl4 as an initiator in the absence of surfactant. Ascorbic acid was used as reducing agent. A pseudoternary phase diagram was constructed at 25 °C using the water titration method in the presence and absence of hexadecyltrimethylammonium bromide (CTAB). Kinetics experimental results showed that the polymerization proceeded in a controlled/‘living’ process as evidenced by a linear increase of molecular weights of polymers with monomer conversion with a relatively narrow polydispersity (<1.35) in all cases and Mn,GPC values of the resulting polymer were in excellent agreement with the theoretical values Mn,th. The polymerization rate increased with the amount of surfactant. However, the polydispersity became broader. The polymerization rate increased with the amount of ligand and decreased with the amount of monomer. In this system, particles of nanoscale (33–51 nm) were prepared. The average particle diameter was found to be affected by the amount of surfactant. The AGET-ATRP of MMA retained the characteristic of living polymerization when the ionic liquid C14MPnBr and catalyst complex were recovered and reused. Living nature of the polymerization was confirmed by the successful homo chain extension experiment. The resultant PMMA was characterized by 1H NMR spectroscopy and gel permeation chromatography techniques.