AbstractA dynamic model is developed to simulate arborescent polyisobutylene (arbPIB) production via self‐condensing vinyl copolymerization in a continuous stirred tank reactor (CSTR). A kinetic Monte Carlo algorithm is proposed that discretizes inflow and outflow separately from reaction steps. The model predicts dynamic changes in monomer and inimer (IM) concentrations, as well as , , and molecular weight distribution (MWD). The CSTR produces arbPIB with broader MWD, compared to a batch reactor using the same recipe and operation time. Predictions of and agree with a previous deterministic model. CSTR operation with high [IM] is unstable because large molecules tend to become even larger as time increases.