Investigation of free-radical polymerization kinetics of styrene and methylmethacrylate with a new azo-peroxydic initiator

SUMMARY Investigation of Free-Radical Polymerization Kinetics of Styrene and Methylmethacrylate with a New Azo-peroxydic initiator In this study, A new free radicalic polymerization initiator, OIigo( 4,4'-azobis- cyanopentanoyl-5-peroxy-2,5-dimethyl-n-hexyl peroxide ), Lu-Ab, was synthesised by the interface condensation reaction of 4-4'-azobis-( 4-cyanopentanoyl chloride ) with 2,5- dimethyl 2,5-dihydroperoxy hexane, in the presence of a base. The molecular weight of the initiator, Lu-Ab, was determined to be 1586 g/mol by using gel permeation chromatograph instrument. Oligoazo-peroxide, Lu-Ab was characterised by infrared (IR) and nuclear magnetic rezonance (NMR) spectrocopies. Peroxygen analysis was made by iodometric and termogravimetric analysis. Because of the difference in thermal stability of azo and peroxide groups, free radical occur by decomposing azo groups of Lu-Ab, first, at 60°C. Active polymer obtained by this way contains peroxide groups in main chain. Styrene and methylmethacrylate were separately polymerised with Lu-Ab at 60°C via- free radical low-conversion-polymerization in order to calculate kinetic parameters. Kinetic parameters, overall rate constants, K, and kt/k«2 = A were calculated from the slopes of the lines obtained from the plots of polymerization rate, root square of initiator concentration and reciprocal degree of polymerization, polymerization rate, respectively. In comparison between Lu-Ab, AIBN and Lu-Ab is an initiator without chain transfer to initiator like AIBN but less effective (e.g. 0.5 time) than AIBN. Key Words; Free Radical Polymerization, Azo-peroxidic Initiators, Active Polymers, Block Copolymers. VI