Effect of Reactant Concentration Variations on the Kinetics of Atom Transfer Radical Polymerization of Acrylonitrile

Abstract

Polyacrylontrile synthesis, via atom transfer radical polymerization, is studied in various initiator concentrations, transitional metal catalyst and different concentrations of CuBr2. The variations of monomer conversion and the lin-earity of semi-logarithmic kinetic profile which is the evidence of living polymerization and constant radical concentration in the reaction medium, were revealed by gas chromatography technique (GC). Gel permeation chromatography (GPC) studies revealed that, the number average molecular weight increases linearly against monomer conversion, an indicative of living nature of the polymerization process. Additionally, the conversion, apparent rate constant and number average molecular weight increased with increased initiator concentration as well as the transitional metal complex concentration. However, addition of CuBr2 lowered conversion, kapp, and the number average molecular weight of polyacrylonitrile. Molecular weight distribution of synthesized polymers broadened with increased initiator concentration and also transitional metal complex concentration. However, addition of CuBr2 has resulted in narrower molecular weight distribution polyacrylonitrile. Moreover, all the samples experienced a drop in PDI value from nearly 2 to almost 1.1 as the reaction progressed.

Keywords

• atrp
• polyacrylonitrile
• reactant concentration
• kinetic
• catalyst