Ex situ Cu(0) nanoparticle mediated SET-LRP of methyl methacrylate/styrene-methyl methacrylate in a biphasic toluene–water system†
The present paper described the first successful use of ex situ copper(0) nanoparticles as an efficient catalyst vis-a-vis using toluene as an effective solvent when doped with water for SET-LRP. Copper(0) nanoparticles (Cu(0) nanoparticles) of ∼5 nm were used as a catalyst with different nitrogen(N)-ligands for the single-electron transfer mediated LRP (SET-LRP) of methyl methacrylate (MMA) using a biphasic water–toluene system as the reaction media. The polymerization was studied by varying the catalyst concentration (0.15 ppm to 28.5 ppm) as well as by varying the mole ratios of monomer, initiator and N-ligands such as N,N,N′,N′′,N′′′-pentamethyldiethylene-triamine (PMDETA), N,N,N′,N′-tetramethyl-1,6-hexanediamine(TMHDA), N,N,N′,N′-tetramethylethylenediamine (TMEDA) and N,N-dimethylhexadecylamine (DMHA). Among the various N-ligands studied PMDETA provided best control over molecular weight while TMHDA gave worst control resulting in a polydispersity of 1.15 and 2.11, respectively at high monomer conversion. The rate of polymerization (kappp) of MMA using Cu(0) nanoparticles/PMDETA at 25 °C and 70 °C was found to be 0.00076 min−1 and 0.0048 min−1, respectively. Under these polymerization conditions, the reactivity ratio of MMA and styrene (St) was found to be 0.41 and 0.23 at 70 °C, respectively.