Synergetic effect of multi-site phase transfer catalysis system mediated free radical polymerization of acrylonitrile – a kinetic study

Abstract

In this work, the kinetics and mechanism of free radical polymerization of acrylonitrile (AN) using potassium peroxydisulphate (PDS-K2S2O8) as a water soluble initiator in the presence of synthesized 4,4'-dihexadecyl-1,1'-bipyridine diiumdichloride (DHBPDDC) as multi-site phase-transfer catalyst (MPTC) has been investigated. The polymerization reaction were carried out under nitrogen atmosphere and unstirred condition at constant temperature 60+1°C in ethyl acetate/water biphasic medium. The effects of variation of monomer(AN), initiator(PDS) and catalyst(MPTC) solvent polarity and temperature on the rate of polymerisation (Rp) were ascertained. The order with respect to monomer(acrylonitrile) was found to be unity. The order with respect to initiator and catalyst was found to be 0.51, 0.48 respectively. However, an increase in the polarity of the solvent has slightly increased the rate of polymerization value (Rp). Based on the results obtained, a suitable kinetic mechanism scheme has been proposed to account for the experimental observations and its significance was discussed. The other thermodynamic parameters such as entropy of activation ((∆S#), enthalpy of activation (∆H#) and free energy of activation (∆G#) have been calculated.