Mathematical Modeling of Arborescent Polyisobutylene Production in Batch Reactors

A novel model describes copolymerization of isobutylene and inimer (initiator-monomer) via living carbocationic polymerization. Six different propagation rate constants and two types of equilibrium reactions are considered. Simplifying assumptions are made to enable implementation in PREDICI, so that the molecular weight distribution (MWD) could be predicted for molecules with different branching levels. Four apparent rate constants were estimated from experimental data with <5 branches per molecule. Model predictions provide a good fit to data, and simulation results show that polymers with high-branching levels and 15 inimer units contribute significantly to the MWD, even though their concentrations are very low.