Grafting onto Cellulose. VII. Graft Copolymerization of Methyl Acrylate by Use of Metal Chelates as Initiators

Abstract

Graft copolymerization of methyl acrylate (MA) onto cellulose has been studied in the presence of Fe(acac)s, Al(acac)s, and Zn(acac)z as initiators in aqueous medium. The percentage of grafting has been determined as a function of concentration of initiators and monomer, reaction time, and temperature. A plausible mechanism for grafting involving prior complex formation between metal chelates and monomers has been suggested. The free radical mechanism for grafting was confirmed by carrying out several experiments in the presence of chain transfer agents such as CCl₄, CHCl₃, CH₃CH₂CH₂SH, and EtsN. All these additives, with the exception of EtsN, were found to suppress grafting. The relative reactivity of different metal chelates toward grafting has been determined and was found to follow the order: Fe(acac)s > Zn(acac)z > Al(acac)s.