Thermal Initiation of methylmethacrylate by Methoxy–oxo- bis [N-(4- bromophenyl) Salicylideneiminato] Vanadium (V)

Abstract

Methoxy – oxo - bis [N - (4-bromophenyl ) Salicylidene – iminato ] Vanadium(V) : [VO (Br C6 H4 N : C H O C6 H4 )2 OCH3 can initiate methylmethacrylatethermally at 80°C . Under the experimental conditions employed, noretardation or inhibition is observed. The order with respect to the initiatorconcentration is (0.5), while the order with respect to monomer concentrationis (1.8) which gives an indication that the rate of initiation is dependent onmonomer concentration.Spectroscopic studies suggest that during the thermal polymerization areduction in the oxidation state of vanadium occurs with heterolytic scission ofthe V- OCH3 bond and this might be induced by MMA molecule which formsintermediate complex between VOL2 OCH3 and methyl methacrylatemonomer before the formation of the primary radical responsible for theinitiation process.Activation energies of polymerization as well as initiation processes in thepresent system were also determined . The tacticity of polymer produced isexamined.According to the experimental results obtained a mechanism of thermalinitiation reaction is proposed.