POLYMERIZATION OF METHYL METHACRYLATE IN PRESENCE OF INITIATING SYSTEMS BASED ON IRON COMPLEXES OF VARIOUS STRUCTURES

Abstract

The features of the radical polymeriation of methyl methacrylate using initiating systems based on benzoyl peroxide and iron complexes with various ligand environments, including ferrocenes containing electron-donating and electron-withdrawing substituents in cyclopentadienyl rings, as well as cyclopentadienyl carbonyl-containing derivatives of iron, have been studied. The influence of the structure of iron complexes on the kinetics of the radical polymerization of methimethacrylate, as well as the molecular weight characteristics of the synthesized polymers, was estimated. It was established that, according to the effect on the methylmethacrylate polymerization rate in the presence of the initiating systems under study, the metal complexes are arranged in the series: 1,1'-dibromoferrocene, bromo (η5-cyclopentadienyl)dicarbonyl iron>1,2,3,4,5-pentaphenyl-1'-(di-tert-butylphosphino- ferrocene)>ferrocene>1-di-tert-butylphosphinoferrocene>1,1-bis-di-tert-butyl-phosphino-ferrocene> bis (η5-cyclopentadienyl) dicarbonyl iron>1–bromo-1′- diphenyl phosphino ferrocene>1-diphenylphosphino-1'-di-tert-butylphosphinoferrocene. Polymers based on polymethylmethacrylate synthesized in the presence of the studied cyclopentadienyl complexes of iron and benzoyl peroxide are capable of acting as macroinitiators in postpolymerization processes. In particular, it was found that polymethylmethacrylate synthesized with the participation of 1,1′-dibromoferrocene and bromo (η5-cyclopentadienyl) dicarbonyl iron in the presence of a peroxide initiator allows the synthesis of postpolymers. Using NMR spectroscopy, it was found that methyl methacrylate-based polymers synthesized both in the presence of the above iron complexes and its analogs obtained by traditional radical polymerization have an atactic structure. Using differential scanning calorimetry, it was shown that methyl methacrylate-based polymers obtained in the presence of cyclopentadienyl and carbonyl iron complexes have a higher glass transition temperature compared to similar polymers synthesized by radical polymerization involving only the peroxide initiator. The temperature of the onset of decomposition of these polymers remains almost unchanged.