Atom transfer radical polymerization (ATRP) of ethyl acrylate: Its mechanistic studies

Atom transfer radical polymerization (ATRP) of ethyl acrylate was carried out in bulk using ethyl 2-bromoisobutyrate as initiator, CuBr as well as CuCl as catalyst in combination with different ligands e.g., 2,2' bipyridine (bpy)and N,N, N',N",N"-pentamethyldiethylenetriamine (PMDETA). In most of the cases very high conversion (72-98%) was achieved. The polymerization was well controlled with a linear increase of molecular weight (M-n(SEC)) with conversion and relatively narrow molecular weight distributions (polydispersity index 1.2-1.3). Use of PMDETA as the ligand resulted in faster polymerization rate (98% conversion in 1 h) than those using bipyridine (72% conversion in 5 h). The MALDI-TOF-MS analysis of poly (ethyl acrylate) (PEA) prepared by using bpy as ligand showed the presence of halogen as the end group. on the contrary, when PMDETA was used as the ligand, the mass analysis showed no trace of this end group.