Polymerization of 4-methylpentene-1 using homogeneous Ziegler–Natta type catalysts: a kinetic study

The kinetics of the polymerization of 4-methylpentene-1 (4MP1) with soluble, homogeneous Ziegler–Natta type catalyst systems, M(acac)3–AlEt2Br (M=Cr, Mn, Fe and Co) at 40 °C in benzene medium was studied. The effect of various parameters such as Al/M ratio, reaction time, ageing time, temperature, catalyst and monomer concentrations on the rate of polymerization and yield were examined. The rate of polymerization increased linearly with increasing monomer concentration with first order dependence. The rate of polymerization with respect to catalyst concentration was found to be 0.5. The polymer yield was maximum at Al/M ratio of 2. The activation energies obtained from linear Arrhenius plots were in the range of 23.40–34.08 kJ mol−1. It was found that the catalytic efficiency of all the catalyst systems towards the polymerization of 4MP1 was almost identical. Based on the experimental results a plausible mechanism is proposed which envisages a free-radical mechanism. Characterization of the resulting polymer product, for all the cases, through FTIR, 1H-NMR and 13C-NMR studies showed isomerized-polymeric structures.