(494d) Monte Carlo Model for Arborescent Polyisobutylene Production in Batch Reactor

A Monte Carlo (MC) model is developed to predict MWD and branching during the production of arborescent polyisobutylene.  The model describes self-condensing vinyl copolymerization (SCVCP) of isobutylene and inimer via living carbocationic polymerization.  The presence of the inimer leads to branching because each inimer molecule contains a vinyl group that can polymerize and an initiating group that can grow a new branch.   Six different propagation rate constants are required to account for two types of vinyl groups and three types of carbocations in the system.  MC model predictions are better than predictions from a previous PREDICI material balance model because fewer simplifying assumptions are required. The MC model predictions reveal that reactions that were previously neglected have an important influence on polymer properties.  The resulting model is helpful for controlling molecular weight and branching levels through judicious selection of initial concentrations and reaction time in the batch reactor.  Future material balance models that will be suitable for parameter estimation will also be discussed.